Expression of vitamin K–associated gene expression in human liver and HEK 293-C3 cells and effects of vitamin K supplementation and doxycycline induction on gene expression in HEK-C3 cells. (A) Gene expression in subconfluent, nondoxycycline-induced, nonvitamin K1–supplemented HEK 293-C3 cells was normalized to its own 18S ribosomal RNA expression and relative fold change determined by comparing to expression in pooled human liver complementary DNA (n = 6), which was set as 1.0. Expression of cytochrome P450’s 2C9 and 4F2 was not detectable in HEK-C3 cells. *P < .5 compared with human liver. (B) HEK-293 C3 cells were plated in regular growth media, with vitamin K1 (VK1) or without supplementation with 50 nM vitamin K1. Twenty-four hours after plating, expression of the F9CH plasmid was induced in some samples by addition of 200 μg/mL doxycycline (Dox). All cells were harvested 48 hours after plating. Gene expression in each sample was normalized to its own 18S rRNA expression and relative fold change determined by comparing to expression in pooled, nondoxycycline-induced, nonvitamin K1–supplemented HEK 293-C3 cDNA (n = 3), which was set as 1.0. Expression of cytochrome P450’s 2C9 and 4F2 was not detectable in HEK-C3 cells. mRNA, messenger RNA.