The endoplasmic reticulum (ER) Ca2+ sensor, stromal interaction molecule1 (STIM1) activates the plasma membrane (PM) channel Orai1 in order to mediate store-operated Ca2+ entry (SOCE) in response to ER store depletion. | Functional consequences of enhanced expression of STIM1 and Orai1 in Huh-7 hepatocellular carcinoma tumor-initiating cells