To confirm the pivotal role of GADD45A in PTPN21-mediated antiapoptotic effects in acute lymphoblastic leukemia (ALL) cells, we restored the expression of GADD45A through lentiviral transfection, while cells transfected with the pHIV7-SFFV-GFP vector served as a control. This evidence concerns the gene PTPN21 and acute lymphoblastic leukemia.