TGFB1 and neoplasm: Several factors are involved in the cross-talk between CSCs and the tumor microenvironment, such as interleukins (ILs) (IL-6, IL-8 and IL-1β), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF) as well as transforming growth factor beta 1 (TGF-β1) which can be freely released into the extracellular space or encapsulated in EVs [14–20].