FTS interrupts ERK activity in human melanoma cells. Human
518A2/N-Ras (L61) melanoma cells (A) and a
vector-transfected control (B and C) were
grown for 24 h in DMEM/10% FCS in the presence of 0.1% DMSO
(zero drug control) or in the presence of the indicated concentrations
of FTS. ERK activity (A and B) was then
determined in cell lysates with MBP as a substrate as described in
Materials and Methods. The phosphorylated MBP bands,
visualized by autoradiography, demonstrate the dose-dependent decrease
in ERK activity. Densitometric analysis (see Materials and
Methods) of data obtained from representative experiments
indicated a decrease in ERK activity of 25–32%, 39–58%, and
65–95%, respectively, in the presence of 5, 10, and 25 μM FTS
either in the 518A2/N-Ras (L61) or the vector-transfected control
cells. The total amount of Raf-1, MEK, ERK remain unaltered in 518A2
cells treated 24 h with FTS (C). Raf-1, MEK, and ERK in cell
lysates were determined by immunoblotting with the corresponding Abs.