FIG. 9.

Induced FAK expression alters Cas phosphotyrosine levels. Tet-FAK(WT)-46, Tet-FAK(F397)-21, and Tet-FAK(F576/F577)-29 cells were either maintained in the presence of tetracycline or induced to express near-equal amounts of WT-, F397, and F576/F577-FAK protein, respectively, and then cells from either attached (Att) (serum starved for 14 h), suspended (Sus), or fibronectin-replated (Fn) (30 min) conditions were lysed in RIPA buffer. FAK (top panel) and Cas (bottom panel) levels were assessed by immunoblot (IB) analysis of 20 μg of total protein from the lysates. Two hundred eighty micrograms of total protein from the same lysates was subjected to immunoprecipitation (IP) by using PY20 antiphosphotyrosine (pTyr) antibody, followed by Cas immunoblot analysis, to determine relative levels of tyrosine phosphorylation of Cas (middle panel).