Genes involved in vitamin D metabolism are expressed in placenta, cytotrophoblast and HEK293 cells but not BeWo cells. rt-PCR images for BeWo: a) CYP2J2, product size 109 bp, b) CYP2R1, product size 96 bp, c) CYP24A1, product size 66 bp, d) CYP27A1, product size 105 bp and e) CYP27B1, product size 438 bp. rt-PCR images for HEK293: f) CYP2J2, product size 109 bp, g) CYP2R1, product size 96 bp, h) CYP24A1, product size 329 bp, i) CYP27A1, product size 105 bp and j) CYP27B1, product size 438 bp. Cyto = placental cytotrophoblast.