CD4 and breast cancer: To solidify the hypothesis that the accelerated tumor growth in R270H tumors is partially attributed to the secretion behavior, which suppressed the CD4 + T lymphocyte-mediated anti-tumor immunity, 4T-1 Con, R270H, R270H + shAP1B1 and R270H NM cells were used to construct the orthotopic breast cancer xenograft model at the mammary pad fat in BALB/c immunocompetent mice.