GRB2 and neoplasm: The other 2 isoforms, p52Shc and p46Shc, can activate the GRB2/SOS complex, thereby allowing activated receptor tyrosine kinases to communicate with the Ras pathway.[39,40] Notably, tyrosine kinase signaling within cancer cells is important in the construction and regulation of an immunosuppressive microenvironment.[41] The protein encoded by PRKCD is activated by diacylglycerols and acts as both a tumor suppressor and as a positive cell cycle regulator.