We observed that YTHDF1 depletion caused significant reduction in tumor size and increasing apoptosis populations compared to the control group and was accompanied with decreasing PKM2 expression in tumor tissues (Fig. 6A–C and Supplementary Fig. S6A, D; Original western blot data 13), indicating that the YTHDF1 knockdown could effectively inhibit the growth of breast tumors in mice by suppressing PKM2. The gene discussed is PKM; the disease is neoplasm.