As let-7 miRNAs including let-7a directly repress IL-6 cytokine production in breast epithelial cells [17], our data suggest a potential activity of XIST by repressing let-7a-2-3p in ALDH- bulk tumor cells to increase IL-6 cytokine production, which in turn promotes ALDH+ CSCs. The gene discussed is XIST; the disease is neoplasm.