POU5F1 and neoplasm: In vivo studies demonstrate that pancreatic cancer stem cells co-cultured with miR-21-overexpressing M2 macrophages display significantly higher tumorigenicity, with increased tumor size and weight, and elevated stemness marker levels, while knocking down miR-21 in M2 macrophage-derived exosomes completely prevents these tumor-promoting effects and reduces Nanog/Oct4 levels in recipient cells [30,32].