Cluster identification of patients for whom induction has failed in T-ALL. (A) Hierarchic clustering of samples (columns) and genes (rows) shows differential expression for patients in the IF (red triangle), RE (black square), and CCR (blue circle) cohorts. Red cells indicate high expression, and blue cells indicate low expression. (B) In 3-dimensional principal component analysis (PCA), 50 T-ALL samples were projected in the feature space based on differential expression for 116 probes. Each sphere represents a sample: red spheres denote IF patients, black spheres indicate RE postinduction remission, and blue spheres show patients who have remained in CCR for longer than 4 years. In panels A and B, the patients for whom induction failed clustered together, indicating a unique and shared genetic signature.