Fig. (2).

Cytosolic Ca²⁺ effects on autophagy. A. Cytosolic Ca²⁺ induces autophagy in non-excitable cells: Rise of cytosolic Ca²⁺ produced by different drugs and Ca²⁺ phosphate-mediated transient transfections activates the CAMKK-β-AMPK-mTOR and CAMKK-β-CAMKI signalling pathways that induce autophagy through various protein targets implicated in this process. B. Cytosolic Ca²⁺ inhibits autophagy in excitable cells: Antagonists of L-, N- or P-type Ca²⁺ channels (verapamil, fluspirilene etc…), and an agonist of L-type Ca²⁺ channels (Bay K-8644) modify cytosolic Ca²⁺ levels and consequently affect the activity of the Ca²⁺-dependent proteases calpains, including their ATG5 cleavage that inhibits autophagy. See text for further details.