Activation of the Ras/MAPK pathway disrupts the
actin cytoskeleton and focal contacts in NRK cells. NRK cells were
transfected with cDNAs encoding various mutant forms of Ras or empty
vector (pDCR). G418-resistant clones were pooled and grown onto
coverslips for immunofluorescence staining, or extracts were prepared
for Western blotting. (A) Whole-cell extracts from NRK/pDCR,
NRK/RasV12S35, NRK/RasV12C40, and NRK/RasV12G37 cells were
immunoblotted with mAb 12CA5 (recognizing the HA tag) and
anti-β-actin to ensure equal loading. The same lysates were analyzed
with antiphospho-MAPK (pMAPK) or antiphospho-Akt (pAkt) antibodies. (B)
NRK cells grown on glass coverslips were fixed. Actin stress fibers and
focal contacts were visualized by indirect immunofluorescence using
phalloidin and antivinculin mAb, respectively. Bar, 20 μm. (C)
NRK/RasV12S35 cells were treated with 0.1% DMSO or 50 μM PD098059
for 48h, then fixed and stained with phalloidin and antivinculin mAb.
Bar, 20 μm.