It is a protein that exists in mammals. Presumably they produced the murine version to put in the mouse. Science journalism screwed up the paper's language, cal

It is a protein that exists in mammals. Presumably they produced the murine version to put in the mouse. Science journalism screwed up the paper's language, calling it a zebrafish protein, when it is a protein that is conserved for all vertebrates. But the function of the protein, and its role in heart regeneration, was identified in zebrafish. > Directly after LAD ligation during MI surgery, hearts were injected twice with 15 μl of AAV9(CMV:GFP) or AAV9(CMV:HA-Hmga1) (1 × 1012 virus particles per mouse) in opposing regions bordering the area at risk of ischemic injury. The paper doesn't say whether the viral vector (AAV9) used the murine or zebrafish Hmga1 sequence, but it is more likely that they used the murine.