Figure 1. Chemical structure and properties of screen identified hits.

A) Compound chemical structures. Compounds are arranged in order of decreasing potency. B) Summary of cellular effects and rationale for compound triage. EC₅₀ values for inhibition of pRB phosphorylation and GI₅₀ values for inhibition of cell growth represent the calculated mean (n = 3). The cell-based immunoassay for the detection of pRB-P-Ser608 (Barrie et al. 2003) was run in HT29 colon carcinoma cells and used to quantify the EC50 for inhibition of pRB phosphorylation at 24 hours, with sulphorhodamine B staining to quantify the GI₅₀ values at 96 hours post compound addition. Protein remaining in wells at 24 hours was determined using bicinchoninic acid assays.