Across TCGA pan-cancer cohorts, CD28 mass-spec protein differs between tumor and matched normal tissue in 4 of 18 cancer types tested, making tumor–normal expression one of CD28’s most consistent transcriptional readouts.
The strongest signal is observed in lung squamous cell carcinoma (LSCC), where CD28 mass-spec protein is more highly expressed in tumor relative to normal tissue. In most cancer types CD28 is over-expressed in tumor, although a few such as HNSC show the opposite, repressed pattern.
LSCC, LUAD, and HNSC are the cancer types where CD28 tumor–normal differential expression is most reproducible.