ERBB3 and melanoma: EV20-Sap in vitro activity on melanoma cells was proportional to HER-3 expression and not affected by the presence of receptor ligand NRG-1β, suggesting the potential benefit of this immune-conjugate in the treatment of most aggressive tumors i.e., those exhibiting a concomitant expression of both HER-3 and its ligand NRG-1β [30].