FURIN and melanoma: Previous analysis in furin knockout (FurKO) or furin and PC7 double knockout (DKO) CRISPR clones of B16-F1 mouse melanoma cells transfected with an INHBA (βA) expression vector established that the conversion of Activin-A precursor (A110) to fully mature 26 kDa form (A30) relies on furin (Fig. 1A).