Identification of biomarkers correlated with sensitivity to dasatinib. (a) Discovery strategy to identify potential predictive and surrogate biomarkers. (b) IC50 determination and sensitivity classification of 16 prostate cancer cell lines to dasatinib. (c) Cluster analysis showing the relative expression pattern of 174 genes that were highly correlated with dasatinib sensitivity/resistance classification of 16 cell lines. The dasatinib-sensitive cell lines are highlighted in red, and the position of three important prostatic cell markers, CK5, PSA and AR, are marked on the heatmap. These genes have differential expression of more than three-fold between the sensitive and resistant groups. (d) Relative baseline gene expression of CK5, PSA and AR in the 16 cell lines. The resistant cells are in black and the sensitive cells are in red. The values on the x-axes are expression level in log2-scale.