Mutations in HERC1 and HERC2 have been detected in leukemia cells (T-cell acute lymphoblastic leukemia (T-ALL) for HERC1 and T-cell prolymphocytic leukemia (T-PLL) for HERC1 and HERC2) and in breast cancer tumors. Here, HERC2 is linked to T-cell acute lymphoblastic leukemia.