The Shc family of proteins consists four members, ShcA, ShcB, ShcC, and ShcD, of which the best characterized to date is ShcA (Rozakis-Adcock et al. 1992). ShcA, or simply Shc, was identified in 1992 as an adaptor protein which linked the activated EGFR (epidermal growth factor receptor) to Ras and the MAP (mitogen-activated protein) kinase cascade (Ravichandran 2001). Shc is expressed as three isoforms which have the molecular weights of 66, 52, and 46 kDa, respectively. These isoforms are designated according to their molecular weight. p66Shc is the longest isoform of the three and also consists of the collagen homology domain (CH2), which is unique to it.