NAADP is now established as a Ca 2+ messenger by recent studies which have shown that it is active in various cells, identified the targeted Ca 2+ stores and demonstrated a stimulus-activated increase in its endogenous levels.
Lee, H. C. (2003, March 4). Calcium signaling: NAADP ascends as a new messenger. Current Biology. Cell Press. https://doi.org/10.1016/S0960-9822(03)00120-9