STAT5B and acute lymphoblastic leukemia: Although we identified only 19 activated STAT5 target genes in pro‐B cells, nine of these genes were shown by GSEA to be significantly enriched as upregulated genes in Pax5Jak2/+ B‐ALL cells compared with control Pax5+/−Cdkn2ab+/− B‐ALL cells (Fig 7H).