Utilizing inducible expression systems in two different cell lines, HEK293 embryonic kidney cells and K562 myeloid leukemia cells, we demonstrated that wild-type (WT) NKLAM, but not the catalytically inactive NKLAM alanine mutant (C301A), inhibited cellular proliferation, as evidenced by reduced cell numbers and decreased metabolic activity. The gene discussed is RNF19B; the disease is myeloid leukemia.