•No effect on proliferation of NK cells in vitro (Dauguet et al., 2010) •Increased NK cell numbers in metastatic MM and other advanced cancer patient (Bartlett et al., 2004b) •Increased numbers of NKp44+ NK cells in MM patients with relapse (Lioznov et al., 2010) •Upregulation of CD56, CD16, CD40L, and LFA1 (Tai et al., 2005; Dauguet et al., 2010) •Downregulation of SOCS1, NKAT2, NKB1, CD158ah, and NKp46 (Dauguet et al., 2010; Gorgun et al., 2010) •Increased cytotoxicity toward MM tumor cells (Davies et al., 2001) •Inhibition of IFN-γ production in activated NK cells (Dauguet et al., 2010). This evidence concerns the gene CD40LG and cancer.