OTSSP167 is an inhibitor (IC50 = 0.41 nM) of maternal embryonic leucine zipper kinase (MELK) with potential antineoplastic activity. OTSSP167 binds to MELK, which prevents both MELK phosphorylation and activation, thus inhibiting the phosphorylation of downstream MELK substrates. This may lead to an inhibition of both cell proliferation and survival in MELK-expressing tumor cells. MELK, a serine/threonine kinase, is involved in cancer cell survival, invasiveness and cancer-stem cell formation and maintenance; it is highly upregulated in various types of cancer cells and absent in normal, healthy cells. MW: 487.42. Purity ≥98% by HPLC