CAMK4 and liver cancer: Although it has not been demonstrated that CaMKIV directly phosphorylates mTOR or S6K in L cells, a previous study reported that CaMKKβ could serve as a scaffold to assemble CaMKIV with key components of the mTOR/S6K pathway and promote liver cancer cell growth (Lin et al., 2015), which lended support to the CaMKKβ/CaMKIV-mTOR signaling in our study.