A model for transcriptional regulation in mitosis. (left) In mitotic cells, e.g., MDA-MB-231 and WI38 cells, where HSF2 is present, HSF1 and RNAPII are displaced from the hsp70 promoter, which prevents stress-induced expression of Hsp70 and ultimately leads to mitotic problems and cell death. (right) In cells, e.g., K562, MCF7, and HeLa cells, where HSF2 levels are dramatically reduced during mitosis, the hsp70 promoter is accessible to RNAPII and HSF1, thus enabling Hsp70 expression and cell survival upon proteotoxic stress.