A recent study in liver cancer cells HepG2 revealed that 1,25(OH)2D3 inhibits cell proliferation by activating PTEN phosphatase and subsequent inhibition of the PI3K/Akt/mTOR pathway [65], in agreement with our results showing that calcitriol implicates HIF-mediated downregulation of Huh7 proliferation under hypoxia (Figure 3D,E). Here, PTEN is linked to liver cancer.