Palbociclib induces ERα expression and promotes NPM/B23 dephosphorylation at multiple sites in endometrial cancer cells. (a,b) Palbociclib (2 µM) was used to treat ARK2 (left panel) and HEC1B cells (right panel) for 24 h. Cell lysates were subsequently resolved on SDS-PAGE and subjected to immunoblotting with antibodies raised against ERα, phospho-NPM/B23 (Ser125), phospho-NPM/B23 (Thr199), phospho-NPM/B23 (Thr234/237), NPM/B23, and β-actin. Densitometry-derived values (bottom) are normalized with the control (-) that was set as 1. Data shown are derived from three independent experiments. β-actin serves as the loading control for normalization. (c) Palbociclib-treated ARK2 cells were collected and mRNA expression levels for ERα, cathepsin D, EBAG9, and TFF1/pS2 were analyzed using real-time qPCR (primers described in the Methods section). Data are expressed as means ± standard errors from three independent experiments. * p < 0.05 compared with controls.