RPS6KB1 and breast cancer: Rapamycin down-regulated the expression of downstream targets of mTOR, such as p4EBP-1, pp70S6K and FASN, whereas the expression of 4EBP-1 and p70S6K did not change (Figure 3C).Therefore, our results suggested that the transcriptional activity of the FASN promoter and the expression of FASN in breast cancer cells were regulated by the PI3K/AKT signaling pathway, mediated by mTOR family members.