Table 1. The selectivity of T521, Poloxin and TQ against the PBDs of Plk1-3 in vitro.

Plks PBD	T521 Apparent IC50	Poloxin Apparent IC50	TQ Apparent IC50
Plk1 PBD	1.22±0.13 μM	4.27±0.69 μM	1.36±0.38 μM
Plk2 PBD	>500 μM	15.62±2.26 μM	3.65±0.96 μM
Plk3 PBD	>500 μM	46.68±3.55 μM	18.86±1.32 μM