In vitro sensitivity to PR-104A in a panel of BCP-ALL and T-ALL xenografts. Xenograft cells were cultured for 48 hours in increasing concentrations of PR-104A (0.1-100 μM). Samples were then assayed with resazurin to determine viability based on mitochondrial activity. (A) The IC₅₀ is plotted for the T-ALL and BCP-ALL xenograft panels. (B) Dose response curves of the viability of cells are shown at the different concentrations of PR-104A for the same xenografts that were used in vivo from Figure 1C-D. (C) In vitro and in vivo sensitivity to PR-104A showed a significant correlation in the 7 xenografts examined. Data represent the mean ± SEM of IC₅₀ values for an individual xenograft from a minimum of 3 independent experiments.