CD8A and melanoma: Our finding that Activin-A only indirectly inhibited CD8+ T cell proliferation agrees with earlier reports that it does not alter the proliferation of CD8+ T cells or their IFNγ expression, or that it may do so only indirectly.23 38 Lastly, analysis in B16.OVA melanoma revealed that depletion of CD8+ T cells abolishes the tumor-promoting activity of INHBA.