Nine proteins were found down-regulated in PML−/− MEFs which includes: (1) promyelocytic leukemia, (2) N-myc downstream regulated 1 gene (NDRG1), (3) calcyclin binding protein (CACYBP), (4) cofilin 1, non-muscle (CFL1), (5) Ras suppressor protein 1 (RSU1), (6) triple functional domain (PTPRF interacting) (TRIO), (7) citron (CIT), (8) annexin A4 (ANXA4) and (9) ubiquitin-conjugating enzyme E2M (UBE2M). Here, UBE2M is linked to acute promyelocytic leukemia.