Fig. 4.

Effect of calcitriol treatment on RFC and P-gp expression in Folr1 KO mice. Significant increases in Slc19a1 (A, RFC) and Abcb1a (B, P-gp) mRNA were observed in isolated brain capillaries, liver, duodenum, and/or kidney of mice treated with calcitriol (2.5 μg/kg) compared with vehicle (corn oil). Results are presented as mean ± SEM for n = 3 independent experiments (total of 8 to 9 animals per group). Asterisks represent data points significantly different from vehicle (*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001).