C3 and breast cancer: We investigated a well-established murine TNBC model, C3(1)-Tag mice, that develops tumors which exhibit a similar gene expression pattern and histopathological characteristics as human basal-like breast cancers.13 Mice in this model exhibit a dichotomous pattern of tumor progression.6 We harvested plasma at baseline and at two additional pre-clinical time points from mice bearing slow- versus fast-growing tumors which resulted in 13 proteins in common between both human and mouse cohorts (Fig. 2b, supplementary Fig. S4).