IL15 and neoplasm: To generate NK cells with anti-tumor activity ex vivo, we cultured murine bone marrow (BM) cells with IL-15 and IL-12, since IL-15 is an NK cell growth and survival factor and both cytokines enhance IFN-γ production and the cytotoxicity of NK cells (Kennedy et al., 2000; Lodolce et al., 1998; Marcenaro et al., 2005).