Ned 19 is a selective membrane-permeant non competitive NAADP antagonist and inhibits NAADP-mediated Ca2+ signaling, with an IC50 of 65 nM. Ned 19 strongly inhibits tumor growth and vascularization as well as lung metastases in mice. Ca2+ Ned 19 (25-100 μM; 24-72 hours) reduces cell proliferation. Ned 19 (25-100 μM; 24-72 hours) reduces markedly the cell number. Ned 19 (25-100 μM; 24-72 hours) reduces the S phase percentage and increases of the G0/G1 phase percentage evaluated by cell cycle analysis. Ned 19 (25-100 μM; 24-72 hours) induces cell apoptosis a time-dependent manner. Ned 19 (25-100 μM; 24-72 hours) reduces expression of N-cadherin and increases expression of E-cadherin, affecting the cell migratory behavior. Cell Proliferation Assay Cell Line: B16 cells Ned 19 (i.p.; 5 mg/Kg/every second day; 4 week) impaires severely tumor growth. Animal Model: Adult male C57BL/6 mice