Active Motif's FK-866 HCl is a Nicotinamide phosphoribosyltransferase (Nampt) inhibitor (Ki = 0.4 nM). FK-866 is a highly specific non-competitive inhibitor of Nampt causing gradual NAD+ depletion. It induces tumor cell apoptosis and causes premature senescence in normal human smooth muscle cells which may be linked to decreased activity of the NAD+-dependent enzyme SIRT1. FK-866 HCl extends the lifespan of human cells, and it is cell permeable.