Compounds from the Prestwick library. (A) Prestwick compounds identified in the screen. Boxes indicate compounds with antimitotic activity. (B) Growth rate-dependence of toxicity. Left: 24-h toxicity of DUX4 against cells growing in media of different serum concentrations. Right: Toxicity of DUX4 expressed as relative viability at 500 ng/mL dox compared to no dox. Note that as cells grow more slowly, the relative difference in viability between control and DUX4-induced cells diminishes.