Expression of P3H1, P3H2, P3H3, and prolyl 3-hydroxylation complex components CRTAP and peptidyl prolyl cis-trans isomerase B (PPIB) in 293-HEK cells. Expression of P3H1, P3H2, P2H3, CRTAP, and GAPDH expression was ascertained by RT-PCR analysis of RNA from MB436 cells (top panel), a cell line previously shown to be positive for expression of all three P3Hs (43), and from 293-HEK cells (bottom panel). Positions of size markers, given in base pairs (bp), are shown to the left of each panel.