Cd2+ triggers TCF4 up-regulation in kidney PTC. (A) TCF4 protein expression was increased by Cd2+ in whole cell lysates from PTC. (B) RT-PCR of mRNA was performed with primers specific for rat TCF4 in WKPT-0293 Cl.2 cells without (ctl) or with Cd2+. Cd2+ increased TCF4 gene expression. (C) TCF4 expression in whole cell lysates of ~50% confluent and 100% confluent cells ± Cd2+ (25 μM for 6 h) by immunoblotting confirmed TCF4 up-regulation induced by Cd2+ in subconfluent cells. (D) Actinomycin D abolished Cd2+-induced TCF4 up-regulation. PTC were treated with or without Cd2+ (25 μM) ± actinomycin D (ACT) (10 μg/ml, 1 h pre-incubation), a transcriptional inhibitor. Expression of TCF4 protein was determined in whole cell lysates of WKPT-0293 Cl.2 cells by immunoblotting.