In conclusion, the present study provides the first demonstration that TSA directly inhibits the proliferation of endothelial cells via STAT5A-mediated transcription repression of proliferation-related genes including BIRC5, CKS1B, and NDC80. Additionally, the TSA–STAT5A–BIRC5, CKS1B, and NDC80 axis also worked in cancer cell angiogenesis models. Here, STAT5A is linked to cancer.