We used our own standalone implementation of the COMPARE method. For each tested compound, we compiled a vector of activity data, -log(GI50), across different cells from the NCI collection. These vectors were normalized and correlation coefficients were calculated between colchicine as the reference compound and the tested compounds, as described previously. All the compounds from the database were arranged in order of decreasing correlation coefficient. The structures of the top 200 compounds with the highest correlation to colchicine were manually inspected.