To further explore the specific mechanism underlying the effect of HTR1A on breast cancer, RNA‐seq was performed in LM2 pCDH and HTR1A‐pCDH, 4173 pCDH and HTR1A‐pCDH stable overexpression cells, and the transforming growth factor‐β (TGF‐β) pathway and epithelial to mesenchymal transition (EMT) pathway were enriched by kyoto encyclopedia of genes and genomes (KEGG) and gene set enrichment analysis (GSEA), Figure3a,b). The gene discussed is TGFB1; the disease is breast cancer.