Vitamin D Receptor Is Not Essential for Extracellular Signal-Related Kinase Phosphorylation by Vitamin D3 in Human Caco-2/TC7 Cells

Vitamin D3 initiated rapid extracellular signal-related kinase (ERK) phosphorylation, but the contribution of vitamin D receptor (VDR) to this event is unclear. We investigated the use of RNA interference (RNAi) to knockdown VDR. RNAi downregulated VDR as well as its targeted gene expression, but vitamin D3 dependent ERK phosphorylation remained. Thus VDR might not be involved in ERK phosphorylation by vitamin D3.