ML216 (CID-49852229) is a small molecule inhibitor of BLM helicase (IC50: 1.8 μM). It showed 28-fold selective against the related helicases RECQ1, RECQ5, and E. coli UvrD (IC50s > 50 μM).

BLM:1.8 μM

Cells were treated with BLM inhibitors at the indicated concentrations for up to 72 hr. At each time point, the WST-1 reagent (a pale tetrazolium derivative converted to an intensely-colored formazan product by the action of mitochondrial dehydrogenases) was added, and after a 4 hr incubation the plates were analyzed optically at 450 nm with a reference wavelength of 690 nm [2].