JS-K is a nitric oxide (NO) donor that reacts with glutathione to generate NO at physiological pH. It inhibits proliferation of HL-60 cells (IC50 = 0.5 uM), which is prevented by the glutathione precursor N-acetyl-L-cysteine , and inhibits growth of the solid tumor cell lines PPC-1, DLD-1, and Meth A. It decreases tumor volume by over 50% in an HL-60 mouse xenograft model when used at a dose of 4 uMol/kg, i.v., three times per week. JS-K inhibits proliferation, induces apoptosis, and disrupts the cell cycle of Jurkat T acute lymphoblastic leukemia cells. It also induces S-nitrosylation of β-catenin followed by dose-dependent degradation of nuclear β-catenin and S-nitrosylated nuclear β-catenin levels.