PLX4720-induced MEK-ERK1/2 hyperactivation occurs rapidly and regulates FAK serine 910 phosphorylation. (a) Sbcl2, WM1361A and WM1366 cell lines were treated with DMSO (−), 1 μM PLX4720 or 10 μM U0126 for 16 h. Lysates were analyzed by western blotting (Boisvert-Adamo and Aplin, 2006) using antibodies for (p)FAK-S910 (Biosource Int, Camarillo, CA, USA), (p)FAK-Y397 (Bd Biosciences, San Jose, CA, USA), and total FAK (Cell Signaling Technology). (b) Sbcl2 and WM1366 cells were treated with 1 μM PLX4720 for 15 min to 20 h. Lysates were analyzed by western blot analysis for (p)MEK, MEK, (p)ERK1/2 and ERK1/2.