Co-cultivation with target cells such as BALL-1 (CD19+ CD20+), REH (CD19+ CD20−), and Jurkat (CD19− CD20−) or other blood tumor cells (Fig. 2E and Additional file 1: Fig. S1b) at diverse effector-target (E: T) ratios for 4 h revealed the cytotoxicity of UCB-NK cells against various blood tumor cells. The gene discussed is CD19; the disease is neoplasm.