BI-2536 is a potent Plk1 inhibitor with IC50 of 0.83 nM, BI2536 shows 4- and 11-fold greater selectivity against Plk2 and Plk3 and also is a BRD4 inhibitor (IC50= 25 nM).

Rigosertib Sodium (Random Configuration) is a non-ATP-competitive inhibitor of PLK1 with IC50 of 9 nM in a cell-free assay. It shows 30-fold greater selectivity against Plk2 and no activity to Plk3.