Fig. 2. Activation of SFKs and EGFR in serum-starved 5637 cells. Whole cell extracts (300 µg/lane) were prepared from carcinoma 5637 cells that had been cultured in normal (10% FCS, denoted `+') or serum-free conditions (for 24 hours, denoted `–') and subjected to immunoprecipitation (IP) with anti-Src antibody, anti-Yes antibody, anti-Fyn antibody or anti-EGFR antibody as described. The immunoprecipitates were analyzed by immunoblotting with the homologous antibody (Src, Yes, Fyn, or EGFR), anti-activated SFK antibody (pY418), an antibody that recognizes the inactive, carboxyl-terminal tyrosine-phosphorylated form of SFKs (pY529) and anti-phosphotyrosine antibody PY99. Asterisks indicate the positions of each protein.