TMPRSS6 and anemia (phenotype): As zebrafish hjv functioned as a BMP co-receptor in vitro and the message appeared to be present at a low level in embryonic hepatocytes, we hypothesized that matriptase-2 (mtp2) may be inhibiting the effect of hjv. Morpholino knockdown of mtp2 has previously been shown to induce anemia in zebrafish embryos,[17] although mtp2′s effect on hepcidin expression and the genetic interaction between mtp2 and hjv in zebrafish embryos have not been evaluated previously.