Figure 1. Steroid receptors and cell cycle regulatory kinases during the cell cycle.

Protein expression (in light blue) and transcriptional activity (in dark blue) of steroid receptors (SRs) and coactivators (ERα, AR, PR, GR and AIB1) during different phases of the cell cycle are shown. During G1/S or S/G2 transition, SR and coactivators generally have high levels of protein expression and transcriptional activities. Both are decreased as the cells progress through G2/M. SRs directly interact with cell cycle kinases (Cyclin D/E/A) to drive G1-S progression. While maintaining the fidelity of cell division, G2/M kinases (PLK1, Aurora A, cyclin B and CDK1, etc.) fine-tune transcriptional levels and protein stability of SRs (ER, AR).