In human primary hepatocytes, depletion of both ActR2a and BMPR2 markedly decreased basal hepcidin mRNA levels and blocked the ability of BMP6 to induce hepcidin gene expression. Human primary hepatocytes were transfected with nontargeting siRNA (siNC) or siRNAs directed against BMPR2, ActR2a, or both. Forty-eight hours later, cells were stimulated without or with BMP6 (10 ng/mL) for 4 hours. RNA was extracted to measure the expression of the genes encoding ActR2a (A), BMPR2 (B), and hepcidin (C, with a logarithmic y-axis). ANOVAs P < .0001; *P < .007 vs siNC without BMP6; ^#P < .0002 vs siNC with BMP6; ^§P < .0001 vs siBMPR2 without BMP6; ^ΦP < .05 vs siActR2a without BMP6; ^†P < .0001 vs siBMPR2 with BMP6; ^††P < .005 vs siBMPR2 and siActR2a, with BMP6.