FIGURE 7.

Mitf isoforms regulate genes involved in signaling. A, Quantitative PCR analysis of genes encoding signaling proteins in Mitf isoform-cells compared with vector alone, wild-type (Mitf ^+/+), and Mitf^−/− cells. Expression is normalized to β-actin. All Mitf isoforms regulate the expression of RSK and SLAP. The receptor tyrosine kinase, c-Kit mRNA is increased about 4-fold in wild-type cells (^+/+) compared with Mitf^−/− cells; however, only the a-isoform restores c-Kit expression to wild-type levels. Values (Relative Expression) are expressed as relative ratios to expression of Mitf^−/− cells on the y-axis (described in Materials and Methods). Data are expressed as the mean result of experiments performed in triplicate. Error bars indicate SD. B, Flow cytometry analysis for c-Kit protein expression shows a moderate impairment of c-Kit in Mitf^−/− cells (dark line) compared with Mitf ^+/+ cells (shaded histogram). Only the a-isoform restores c-Kit expression to wild-type levels, consistent with quantitative PCR data. Dark shaded histogram denotes isotype Ab control.