The transcription factor TAp73, a transcriptionally active isoform of p73, has high structure and function similaritieswith its homolog p53, therefore, are thought to be a cancer therapy candidate target. However, there is still a controversy about the tumor suppressor role of TAp73, since it has been found in numerous studies that TAp73 expression is elevated in different cancers. Thus, we take effort to clarify the influence of TAp73 on gastric cancer (GC) chemotherapy. Multiple cell lines of GC such as SNU-1, SNU-3, and AGS were applied to investigate expression of TAp73. Flow cytometry was utilized to detect apoptosis, revealing how TAp73 overexpression affected anticancer drug (ACD). Additionally, we explored how TAp73 overexpression influenced apoptotic cells of neoplastic tissues and tumor size of nude mice in vivo. Our results indicated that TAp73 was down-regulated in GC cells after chemotherapy drugs treatment. Besides, enforced expression of TAp73 affects chemotherapeutic drugs induced GC cell apoptosis, which is dependent on p53. The expression of TAp73 was regulated by its transcription factor, E2F1, in response to chemotherapy drugs. Our in vivo xenograft results also suggested that transfection of TAp73 affects the tumor suppression effect of 5-FU. Consequently, the findings of our study demonstrate that E2F1 and TAp73α are oncogenic and throw light upon the underlying mechanism of their role against apoptosis.