A. BMP6 mRNA levels were measured by qRT-PCR in mutants and in their respective WT strains before and after chronic iron loading. Expression increased significantly in all the groups tested (p values: C57BL/6=0.018, 129S6=0.026, FVB<0.001, Hfe p=0.037, Tfr2 =0.001, and Hjv =0.003). Medians and interquartile range are shown. BMP6 was also measured in mice before and after 1 day iron feeding, but the increase did not reach statistical significance. B. BMP6 mRNA expression is proportional to the liver iron load (non-heme iron) in WT and mutant mice.