STAT3 and breast neoplasm: Moreover, S. aureus appeared to attenuate the immunosuppressive functions of mMDSCs, gMDSCs, and PMNs by downregulating phosphorylated signal transducer and activator of transcription 3 (STAT3) (supplementary Fig. 9f, g).(36) Given significant correlation between intratumoral Staphylococcus and the cold metabolite NADH in human breast tumors (Fig. 3), we next investigated whether S. aureus functionally affects total NAD level.