Finally, we conclude that the depression of Ca2+ signals cannot be attributed entirely or substantially to reduced expression of IP3R proteins, because mean agonist-evoked Ca2+ responses across four FXS and TS lines were about 22% of matched controls, whereas western blots showed mean IP3R levels to be about 80% of controls and uncorrelated with the extent of Ca2+ signaling depression in these different cell lines. Here, ITPR3 is linked to fragile X syndrome.