Immature NK cells (i.e., Stage 1–3 including early progenitors which are CD56 negative, CD94 negative and CD16 negative produce higher levels of cytokines with little to no cytotoxicity while more mature NK cells (i.e., Stage CD56 bright/CD94 positive, low to absent killer immunoglobulin-like receptor (KIR), high inhibitory CD94/NKG2A heterodimer positive and Stage 5 CD56dim, CD94 negative, high KIR, and CD16 positive) have anti-tumor natural cytotoxicity as well as antibody dependent cellular cytotoxicity (ADCC) in the presence of CD16 expression (8). The gene discussed is KLRD1; the disease is neoplasm.