Holotransferrin specifically induces hepcidin mRNA expression in mouse primary hepatocytes. Primary hepatocytes were isolated from both wild-type (A) and MyD88-deficient mice (B) on C57BL/6J background. Hepatocyte cultures were treated with 30 μM apotransferrin or holotransferrin or with 0.25 EU/mL or 100 EU/mL LPS endotoxin standard. Means and standard deviations are shown. (A) In wild-type hepatocytes (n = 8 mice), only holotransferrin and 100 EU/LPS induced hepcidin mRNA expression (P < .001). (B) In MyD88-deficient hepatocytes (n = 4 mice), only holotransferrin induced hepcidin mRNA expression (P = .003) and LPS suppressed it (P = .03).