S100A9 and neoplasm: To address whether BAP18 promotes TNBC tumor growth through regulating S100A9, we re-expressed Flag-S100A9 in LM2-4175 cells stably expression shBAP18 (Fig. 7A), and then 1 × 106 cells were injected into the mammary fat pad of 6-week-old female BALB/c athymic nude mice.