Fig. (7) Transient transfection of parental or drug resistant DU-145 cells with ERK1/2 specific siRNA probes as compared to non-target probes, decreases (silences) the expression level of ERK1/2 mRNA in both cell types and also decreases the amount of ERK1/2 protein in both. Phosphorylated ERK1/2 is also decreased in resistant cells (Resistant), but is elevated in drug-untreated parental controls (Parent). Panel A: Real Time PCR determination of relative ERK1/2 mRNA levels in drug naïve parental cells transfected either with specific or nonspecific siRNA probes. Panel B: Real time PCR determination of relative ERK1/2 mRNA levels in drug-resistant cells transfected either with specific or non-specific probes. Panel C: Western blot analysis of extracts taken from siRNA transfected parental or resistant cells with ERK1/2 specific or non-specific probes. Data in panels A and B represent means ± S.D. of three independent determinations. The results in Panel C are representative of three individual blots.