TGFB1 and colorectal carcinoma: We found that the elevated transcription of Snail, Slug or ZEB1 and the enhanced motility capacity of CRC cells resulting from circPTEN1 knockdown could be drastically inhibited by Ski overexpression (Fig. 6D, E and F), further confirming that circPTEN1 suppresses CRC metastasis by inhibiting TGF-β1/Smad-mediated EMT.