In T-cell acute lymphoblastic leukemia (T-ALL), HOXA9 acts as an oncogene by cooperating with JAK3/STAT5 at the transcriptional level through upregulating the expression of downstream genes, such as PIM1 and activator protein-1 (AP-1), thereby affecting cell survival and apoptosis [147]. Here, HOXA9 is linked to T-cell acute lymphoblastic leukemia.