Knockdown of SRF inhibits MKL1-induced increase in ploidy in response to TPA. HEL/MKL1 cells (A) and HEL/control cells (B) were treated with Dox and siRNA against SRF as indicated, and ploidy was measured over time (x-axis) after TPA addition. The y-axis represents the percentage of cells that had a ploidy of 8N. *P < .005, negative siRNA + Dox versus the rest of the groups.