These observations were further validated by immunohistochemistry in 38 FFPE surgical breast tumor samples and 150 samples on tissue microarray (Fig. 3f–h, Supplementary Table 3), in which FOXC1 upregulation in TNBC was significantly associated with higher grade (P = 9.72 × 10−5, Chi-square test), Ki67 (P = 6.14 × 10−4, Chi-square test) and tumor-infiltrating lymphocytes (P = 1.54 × 10−6, Chi-square test). Here, FOXC1 is linked to breast neoplasm.