IL15 and cancer: At 72 h, only 19% of the B16F10 cells or 44% of the CT26 cells showed a detectable IL-15GFP signal, but the expression levels of IL-15RαGFP alone or codelivery of IL-15 + IL-15RαGFP (IL-15:IL-15RαGFP) were higher than that of IL-15GFP in both cancer cells (Figure 2B).