RUNX1 and melanoma: miR-34a promotes the proliferation of MDSCs by inhibiting their apoptosis,139 whereas miR-9 regulates the differentiation and function of MDSCs by targeting runt-related transcription factor 1 (Runx1).140 Conversely, the lack of miR-155 in B16-F10 melanoma and Lewis lung carcinoma cell lines leads to the recruitment of MDSCs in the TME and subsequently enhances immunosuppression.141