Expression and role of p-ERK1/2 in adult ALL samples. (A) Distribution of p-ERK1/2 expression in 131 ALL samples. (B) Three examples of primary ALL characterized by negative or intermediate and high p-ERK1/2–positive expression (flow-cytometry assay). (C) Correlation between p-ERK1/2 expression and WBC count in 131 ALL samples (P = .026; r = 0.20). (D) Correlation between p-ERK1/2 expression and response to treatment. A trend (P = .069) was found between lower phosphoprotein level (continuous variable) and higher probability of achieving CR.