BRCA1 and breast cancer: Similar to human IRIS, mouse Brca1-Iris (hereafter Iris) is overexpressed in mouse breast cancer cell lines, especially those of the TNBC subtype (e.g., 4 T1, generated from a spontaneous BALB/c TNBC tumor [43] and EO771, generated from a spontaneous C57BL/6 TNBC tumor [44]) (not shown).