CD28 & MUC1

MUC1 encodes a cell surface glycoprotein that functions as a protective mucin, contributing to the barrier function of epithelial tissues. It is involved in protecting the gastrointestinal, respiratory, and genitourinary tracts from pathogens. MUC1 is also implicated in cancer progression, particularly in breast, lung, and pancreatic cancers, where it can be overexpressed, influencing cell signaling and tumor growth.

CD28 is a co-stimulatory receptor found on T cells that plays a key role in T-cell activation and survival. It is a transmembrane protein expressed on naïve and activated T cells, binding to B7-1 (CD80) and B7-2 (CD86) on antigen-presenting cells (APCs). This interaction provides the necessary secondary signal for full T-cell activation, alongside T-cell receptor (TCR) engagement with antigen-presenting major histocompatibility complex (MHC). CD28 signaling promotes cytokine production, T-cell proliferation, and survival. In the absence of CD28 signaling, T cells may become anergic (non-responsive). Because of its role in immune regulation, CD28 is a target for therapeutic interventions in autoimmune diseases, transplantation, and cancer immunotherapy.