Figure 2.

Store-operated Ca²⁺ in cancer stem cells. Cartoon depicting a hypothetical mechanism of SOCE in CSC, based on our current knowledge in non-tumoral cells: (a) when intracellular Ca²⁺ stores are filled, STIM proteins remain in their quiescent conformation; (b) small changes in luminal Ca²⁺ concentration are controlled by STIM2, briefly activating CRAC channels to replenish the reservoirs; (c) massive Ca²⁺ store depletion triggers the activation of STIM proteins and the channels in plasma membrane, resulting in the critical increase in cytosolic Ca²⁺ required for tumorigenic responses.