MTOR and breast cancer: It is also relevant that OV treatment significantly reduced the miR-21-5p level within CSC_EVs alongside STAT3 and mTOR, especially as evidence abounds that increased miR-21 levels in breast cancer cells are associated with inhibition of tumor suppressors, such as PDCD4 and PTEN, coupled with amplification of mTOR signaling and promotion of CAF transformation via suppression of Smad7 [18,44,45].