CD34 and cancer: As RSKs have been reported to play a key role in cellular proliferation and survival in cancer cells [9–12], we determined the expression levels of total RSKs (1/2/3) and phosphorylated RSK (T573) proteins in leukemic cells from 483 pediatric AML patients relative to normal CD34+ bone marrow samples (Supplementary Table 1) with Reverse Phase Protein Analysis (RPPA).