PLK1 and cancer: The FOXM1 transcription factor is a proto-oncogene involved in cell cycle progression, cell proliferation, tumorigenesis and cancer progression [27], and many of its target genes (> 20) were downregulated in paclitaxel-residual MDA-MB-231 cells including AURKB, CCNB1, PLK1, PLK2, and the kinesin KIF20A (Figure 4B, 4H, 4I).