POP4 and cancer: Upon PLEKHF1, POP4 or TSHZ3 siRNA-mediated gene silencing, slight but not statistically significant increases in the subG1 fraction and decreases in the G2/M fraction were observed in cancer cells with (that is, MDA-MB-157 and HCC1569) or without (that is, MDA-MB-231, JIMT1, ZR75.1 and BT474) 19q12 amplification (Additional file 4 Figure S2).