WT145 cells, KO240 cells and three clones of KO240 cells stably expressing hVDR (KOhVDR1, KOhVDR2, KOhVDR4) were treated with 100nM 1,25D or ethanol vehicle for 24h. RNA was isolated and used for real-time PCR evaluation of Cyp24, Cib2, Prelp and Enpp1. Data are normalized against 18S and expressed as fold change (1,25D treated vs control) for each cell line. Each bar represents mean ± standard error of 2–3 independent samples analyzed in duplicate. *p< .05, control vs 1,25D treated for each cell line.