To validate the roles of YTHDF1 in breast cancer progression, we further monitored the effect of YTHDF1 knockdown on the tumorigenicity of breast cancer cells using BALB/c mice with subcutaneous breast tumors, which were established by injecting YTHDF1 shRNA-treated 4T1 cells into 4-week-old female BALB/c mice. The gene discussed is YTHDF1; the disease is breast cancer.