CD4 and breast neoplasm: To investigate the role of TSLP in the early stages of tumor development in other breast cancer models, we developed a T cell/primary tumor transfer system in which Rag1KO mice received WT (test) or TslprKO (control) CD4+ T cells followed by primary breast tumor implantation from K14-Cre Brca1f/f p53f/f TslprKO mice into their abdominal mammary fat pad.