CD4 and ocular melanoma: Of all the components investigated, removal of forskolin partially and removal of nicotinamide almost completely abolished the suppressive effect of OM on T cells and removal of nicotinamide even increased the number of CD137+ cells (CD4+ CD137+ 10.4% in OM-nic vs 3.3% in TM+, p < 0.01; CD8+ CD137+ 8.6 vs 2.9%, p < 0.05) (Fig. 1c and Supplementary Fig. S2).