WB: 1:1000

The epidermal growth factor (EGF) receptor is a 170 kDa transmembrane tyrosine kinase and member of the HER/ErbB protein family. Ligand binding results in receptor dimerization, autophosphorylation, activation of downstream signaling and lysosomal degradation (1,2). Phosphorylation of EGF receptor (EGFR) at Tyr845 in the ki¬nase domain is implicated in stabilizing the activation loop, maintaining the active state enzyme and providing a binding surface for substrate proteins (3,4). c-Src is involved in phosphorylation of EGFR at Tyr845 (5). The SH2 domain of PLCbinds at phospho-Tyr992, resulting in activation of PLC-mediated downstream signaling (6). Phosphorylation of Tyr1045 creates a major docking site for c-Cbl, an adap¬tor protein that leads to receptor ubiquitination and degrada¬tion following EGFR activation (7,8). The GRB2 adaptor protein binds activated EGFR at phospho-Tyr1068 (9). A pair of phosphorylated residues (Tyr1148 and Tyr1173) provide a docking site for the SHC scaffold protein, with both sites involved in MAP kinase signaling activation (2). Phosphorylation of EGFR at specific serine and threonine residues attenuates EGFR kinase activity. EGFR carboxy terminal residues Ser1046 and Ser1047 are phosphorylated by CaM kinase II; mutations to either of these serines upregulate EGFR tyrosine autokinase activity (10). Phospho-EGF Receptor (Tyr1148) Antibody detects endogenous levels of EGF re¬ceptor only when phosphorylated at Tyr1148. This antibody does not cross-react with other tyrosine-phosphorylated ErbB family members