FOLR1 and melanoma: In contrast, a control MOv18 IgE antibody, targeted toward a different antigen, folate receptor-alpha, which is not expressed by A375 melanoma cells, and used here as a nonspecific isotype control, showed much lower T/B and T/M ratios than those of the anti-CSPG4 antibodies at 24–120 h (Figure 5a,b).