ABL1 and breast cancer: To assess in vivo the T cell antileukemic activity in BC CML, we co-transplanted Mir142−/−BCR-ABL LSK (CD45.2, 5000 cells) and Mir142+/+ T or Mir142−/− T cells (CD45.2, 106 cells) into CD45.1 congenic recipients (lethally irradiated to eradicate host T cells; Fig. 4a).