MTOR and hepatocellular carcinoma: Moreover, we found that compared to the negative control siRNA (NC siRNA) transfected HCC cells, rapamycin treatment diminished the upregulation of both p-CAD and phosphorylated p70S6K (p-p70S6K) in the siASS1 group (Fig. 5C), suggesting ASS1 reduction upregulates CAD phosphorylation via the mTOR/p70S6K signaling pathway.