Inoculation of 4T1 cells in mammary fat pad of BALB/c mice produced primary tumors and could spontaneously metastasize to multiple distant organs, with the disease progression similar to human breast cancer.38 LDHA and LDHB knockout significantly reduced the growth rate of tumors and lung metastasis with the LDHA knockout more prominent (Fig. 6d–f). The gene discussed is LDHB; the disease is breast carcinoma.