(A) Vkorc1 and Vkorc1l1 mRNA expression in C57BL/6J livers at e14.5, e16.5, e18.5, P0, P7, and P15 were measured by quantitative PCR (qPCR) and normalized to Actb (n = 3; mean ± SEM). Copy number was quantified using plasmid DNA containing either Vkorc1 or Vkorc1l1 cDNA as a standard. (B) Protein expression in liver at e16.5, e18.5, P0, P7, and P15 was analyzed by Western blot using antibodies against VKORC1, VKORC1L1, GGCX, or β-actin. Quantification shows arbitrary densitometry units of VKORC1 signal relative to VKORC1L1. (C) VKOR activity in C57BL/6J livers at e16.5, e18.5, P0, P7, and P15 was measured (n = 4; mean ± SEM; 1-way ANOVA tests followed by Bonferroni’s multiple comparisons test; **P < 0.01; ***P < 0.001).