PSIP1 and autoimmune disease: This prediction was proved by the use of electrophoresis mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay which both showed the capability of the p21 promoter with rs2395655 G but not A allele for binding to lens epithelium‐derived growth factor/p75 (LEDGF/p75, also known as PSIP1 and DFS70 autoantigen), a potent survival oncoprotein involved in stress response, autoimmune disease, HIV replication, and cancer progression.24, 25, 26, 27 The regulatory effect of LEDGF/p75 on the p21 expression was further examined in ESCC cells with rs2395655 GG or AA genotype.