Recent research reported that MUC16 could inhibit the anti-tumor activity of the immune cells and cause tumor cell immune escape by acting on the sialic acid-binding immunoglobulin-like lectin-9 (Siglec-9), a brand-new immune checkpoint, on the surface of natural killer cells (NK cells), B cells, and monocytes [8, 9]. The gene discussed is MUC16; the disease is neoplasm.