Restoration of
ROCKI/Rho-kinase expression and activity upon MEK inhibitor treatment
of NRK/ras cells. (A) NRK and NRK/ras cells were maintained in the
absence (−) or presence (+) of 50 μM PD098059 or 25 μM U0126 for
48 h. Rho-GTP levels were then analyzed (representative of two
experiments). (B) Cells were treated as indicated, and whole cell
extracts were immunoblotted using anti-ROCKI,
anti-Rho-kinase, and anti-β-actin antibodies (top panels). The same
extracts were probed with an antiphospho-cofilin antibody, followed by
anti-cofilin antibody, after the membrane was stripped (bottom panels).
(C) Rho-kinase mRNA expression in NRK and NRK/ras cells upon treatment
with PD098059. Rho-kinase cDNAs were amplified by PCR for 15, 20, or 25
cycles from RNAs of NRK and NRK/ras cells incubated in the presence (+)
or in the absence (−) of 50 μM PD098059 for 48 h. As a control,
rat GAPDH cDNA was also amplified (top panel). Densitometry
analysis of Rho-kinase cDNAs amplified for 20 cycles. Data are
representative of three independent experiments (mean ± SD).
Relative Rho-kinase mRNA levels, normalized to GAPDH levels, are
expressed vs. control NRK, which is arbitrarily set to 100% (bottom
panel).