Human and murine germline-derived immortalized cell lines and FACS-sorted very small embryonic-like stem cells (VSELs) and hematopoietic stem cells (HSCs) express functional vitamin D receptors (VDRs). Expression of VDRs was detected in purified mRNA samples from human teratocarcinoma (hNTERA2) and ovarian cancer (hA2780) cell lines (Panel a, left) as well as from the murine embryonal teratocarcinoma (mP19) cell line (Panel b, left) by both real-time and conventional reverse transcription polymerase chain reaction (RT-PCR). The effect of 1,25-dihydroxyvitamin D3 on phosphorylation of p42/44 MAPK and AKTser473 intracellular pathway proteins in hNTERA2 and hA2780 cell lines (Panel a, right) and the mP19 cell line (Panel b, right) was investigated. Cells (2 × 106 cells/mL) were starved for 12 h in their respective basic culture media containing 0.5 % BSA and stimulated afterwards for 5 min with 1,25-dihydroxyvitamin D3 at various concentrations (10−10–10−8 M) or with vehicle (DMSO) only. The experiment was carried out twice with similar results, and representative blots are shown. Panel c The VDR is expressed by sorted VSELs and HSCs. RT-PCR showed expression of the VDR by both murine BM-derived (left panel) and human UCB-derived (right panel) VSELs, HSCs, and MNCs. In all experiments, samples with water only instead of cDNA (−cDNA) and without reverse transcriptase (−RT) were used as negative controls. Representative agarose gels of the RT-PCR amplicons obtained are shown. Each experiment was carried out twice with similar results, and representative blots are shown