Based on the higher proliferation rates observed in STIM1-overexpressing EpCAM(+)CD133(+) Huh7 cells compared to that of STIM1 + Orai1-OE constructs, one may conclude that HCC stem cells might undergo a phenotypical switch process from a quiescent to proliferative stage by increasing ER Ca2+ buffering capacity due to higher levels of Ca2+-binding protein, STIM1. The gene discussed is ORAI1; the disease is hepatocellular carcinoma.