PBK and cancer: Because knockdown of TOPK and MELK revealed much stronger effect on the growth suppression of kidney cancer cells than that of FOXM1 (data not shown), it is almost certain that TOPK and MELK are more attractive molecular targets than FOXM1 to inhibit signaling pathways essential for cancer proliferation, although it remains unclear which will serve as an upstream of others and play more fundamental roles in kidney cancer.