FOS family basal expression. Steady state mRNA levels of FOS (FosB, cFos, Fra1, and Fra2) mRNA and protein expression. (A) Total RNA's were isolated and semi quantitative RT-PCR was performed to determine the mRNA levels of FosB, cFos, Fra1, and Fra2 in prostate cells. L-19 was used as an internal control. (B) Western blot analysis of FosB, cFos, Fra1, and Fra2 in prostate cells. β-actin was used as a loading control.