Intracellular heat shock protein levels and sensitivity to nutlin-3 in primary AML cells. (A) Sensitivity to nutlin-3 (10 μM, 24 hours) in 40 primary AML samples was determined by 3H-thymidine incorporation assay, and samples were analyzed in triplicates. Samples with TP53 mutations are marked with *. Intracellular levels of heat shock proteins Hsp27 (phospho-Ser82), Hsp27 (phospho-Ser15), Hsp40, Hsp60, Hsp70 and Hsp90α for all samples were determined using Hsp/Chaperone 8-plex MultiBead kit and flow cytrometric analysis. Samples were analyzed in duplicates. (B) Median values of heat shock protein levels were determined for the patient samples that were sensitive (10 most sensitive ranging from 18-53% viability of control) and non-sensitive (10 least sensitive ranging from 95-above 100% viability of control) to nutlin-3, and are shown in the figure together with values for individual patient samples. Samples with TP53 mutations are indicated. Mean values are given below. For Hsp27 (phospho-Ser82) and Hsp27 (phospho-Ser15) levels are given as u/ml; for Hsp40, Hsp60, Hsp70 and Hsp90α levels are given as ng/ml.