Quantum-Si and Cell Signaling Technology Partner to Advance Post-Translational Modification Analysis on Proteus™

Quantum-Si Incorporated (NASDAQ:QSI) ("Quantum-Si," "QSI" or the "Company"), a proteomics company redefining protein analysis through single-molecule protein sequencing, today announced a partnership with Cell Signaling Technology ("CST") to advance and validate next-generation protein sequencing and analysis of post-translational modifications ("PTM") on the Proteus™ single-molecule protein sequencing platform. The partnership will focus on integrating CST's PTM detection and immunoaffinity enrichment expertise with Quantum-Si's Proteus workflows to enable site-resolved detection and quantitation of proteins and PTMs for research applications.

CST is a leading supplier of high-quality recombinant monoclonal antibodies, kits, and services for scientific discovery and translational research, and an early pioneer in the development of PTM-specific reagents and enrichment workflows for the analysis of protein regulation and cell signaling. CST's PTMScan^® proteomics technology combines PTM-specific immunoaffinity enrichment with mass spectrometry and bioinformatics to generate high-content datasets for biomarker discovery and drug development research.

As part of the collaboration, CST will leverage its expertise in PTM enrichment, mass spectrometry, and bioinformatics to generate well-characterized PTM-enriched samples and datasets to support the development of Quantum-Si's single-molecule protein sequencing workflows. In the first phase, datasets generated by CST will be used to build and refine Quantum-Si's kinetic signature database and automated analysis methods for the site-resolved detection and quantitation of proteins and PTMs. In the second phase, results from the Proteus platform will be compared with orthogonal mass spectrometry data generated by CST to benchmark performance and support the validation of the Proteus platform's PTM and protein analysis capabilities.

"We are excited to partner with CST on the development and validation of our PTM capabilities on Proteus," said Jeff Hawkins, President and Chief Executive Officer of Quantum-Si. "CST is a global leader in the field of PTM discovery and analysis and being able to leverage their experience and capabilities to accelerate the validation of our technology in this field is an important part of ensuring Proteus is launched with the validated PTM capabilities that customers need."

"At CST, we're focused on enabling deeper insights into the protein regulation and cell signaling events responsible for disease progression," said Roberto Polakiewicz, Chief Scientific Officer at Cell Signaling Technology. "By combining our expertise in PTM biology and antibody-based enrichment with Quantum-Si's single-molecule sequencing technology, we aim to support new ways of interrogating complex biological systems and complement existing mass-spectrometry-based proteomics workflows. We look forward to working with Quantum-Si to bring these capabilities to more researchers."

About Cell Signaling Technology

Cell Signaling Technology (CST) is a different kind of life science company—one founded, owned, and run by active research scientists, with the highest standards of product and service quality, technological innovation, and scientific rigor. Founded in 1999 and headquartered in Danvers, Massachusetts, USA, CST employs over 600 people worldwide. We consistently provide fellow scientists around the globe with best-in-class products and services to fuel their quests for discovery. CST is a company of caring people driven by a devotion to facilitating good science—a company committed to doing the right thing for our customers, our communities, and our planet. www.cellsignal.com

About Quantum-Si Incorporated

Quantum-Si is transforming proteomics with a benchtop platform that brings single-molecule protein analysis to every lab, everywhere. The Company's platform enables real-time kinetic-based detection and allows researchers to move beyond traditional, multistep workflows and directly access dynamic, functional protein insights with unparalleled resolution. By making protein analysis simpler, faster, and more informative, Quantum-Si is accelerating proteomic discoveries to improve the way we live. Learn more at quantum-si.com or follow us on LinkedIn or X.

Forward Looking Statements

This press release includes "forward-looking statements" within the meaning of the "safe harbor" provisions of the United States Private Securities Litigation Reform Act of 1995. The actual results of the Company may differ from its expectations, estimates, and projections and, consequently, you should not rely on these forward-looking statements as predictions of future events. Words such as "expect," "estimate," "project," "budget," "forecast," "anticipate," "intend," "plan," "may," "will," "could," "should," "believes," "predicts," "potential," "continue," and similar expressions (or the negative versions of such words or expressions) are intended to identify such forward-looking statements. These forward-looking statements include, without limitation, the Company's expectations with respect to future performance and development and commercialization of products and services, its anticipated cash runway, anticipated data and product launches (including Proteus), investor confidence in Quantum-Si and our strategic roadmap, and any financial guidance. These forward-looking statements involve significant risks and uncertainties that could cause the actual results to differ materially from those discussed in the forward-looking statements. Most of these factors are outside the Company's control and are difficult to predict. Factors that may cause such differences include, but are not limited to: the inability to maintain the listing of the Company's Class A common stock on The Nasdaq Stock Market; the ability of the Company to grow and manage growth and retain its key employees; the Company's ongoing leadership transitions and succession planning; changes in applicable laws or regulations; the ability of the Company to raise financing in the future; the success, cost and timing of the Company's product development and commercialization activities, including the use and benefit of artificial intelligence in these and other activities; the commercialization and adoption of the Company's existing products and the success of any product the Company may offer in the future; the potential attributes and benefits of the Company's commercialized Platinum protein sequencing instruments and kits and the Company's other products (including Proteus) once commercialized; the Company's ability to obtain and maintain regulatory approval for its products, and any related restrictions and limitations of any approved product; the Company's ability to identify, in-license or acquire additional technology; the Company's ability to maintain its existing lease, license, manufacture and supply agreements; the Company's ability to compete with other companies currently marketing or engaged in the development or commercialization of products and services that serve customers engaged in proteomic analysis, many of which have greater financial and marketing resources than the Company; the size and growth potential of the markets for the Company's products and services, and its ability to serve those markets once commercialized, either alone or in partnership with others; the Company's estimates regarding future expenses, future revenue, capital requirements and needs for additional financing; the Company's financial performance; the Company's defense and initiation of litigation matters; and other risks and uncertainties described under "Risk Factors" in the Company's most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q and in the Company's other filings with the SEC. The Company cautions that the foregoing list of factors is not exclusive. The Company cautions readers not to place undue reliance upon any forward-looking statements, which speak only as of the date made. The Company does not undertake or accept any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements to reflect any change in its expectations or any change in events, conditions, or circumstances on which any such statement is based.

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Investor and Media

Jeff Keyes

Chief Financial Officer

ir@quantum-si.com



CST Media and Press

Rebecca J. Reppucci, MBA

Cell Signaling Technology, Inc.

Senior Director, Global Marketing Communications

Phone: +1-978-880-3334

Email: marketingpr@cellsignal.com