To test the hypothesis that Ca2+ oscillation is a hallmark of CSCs, we applied a panel of potential niche factors, including ATP, epidermal growth factor (EGF)/basic fibroblast growth factor (FGFb)/B27, and interleukin (IL)-6, and assessed the Ca2+ response in the liver CSC line Hep-12 and its matching hepatocellular cancer (HCC) line Hep-11. Here, MRAP is linked to hepatocellular carcinoma.