FIGURE 6.
Growth factor withdrawal increases STAT1 mRNA levels in KPNA1-dependent fashion. A, control or KPNA1-deficient MEFs were exposed to serum-free medium for 0, 12, or 18 h before detection of STAT1 mRNA by real time PCR. The data are shown as the mean fold changes versus control = 1 ± S.E. as determined by the ΔΔCT method. B, control (Ctrl) or KPNA1-deficient MEFs were exposed to serum-free medium for 0 or 18 h before detection of STAT1 protein levels by Western blot. The arrow indicates KPNA1, and the asterisk indicates a protein other than KPNA1 that is detected by the anti-KPNA1 antibody. Shown below are the means of STAT1 normalized to β-actin band densities (± S.E., n = 3). The data represent experiments on two separately derived cultures for each cell type. *, p < 0.05 versus control; †, not significant versus KPNA1−/− control by Student's t test.