. "\"Any process involved in the maintenance of an internal steady state of calcium ions within the endoplasmic reticulum of a cell or between the endoplasmic reticulum and its surroundings.\" [GOC:mah]" . . "endoplasmic reticulum calcium ion homeostasis" . "calcium ion homeostasis in endoplasmic reticulum" . "calcium ion homeostasis in ER" . "endoplasmic reticulum calcium ion concentration regulation" . "ER calcium ion concentration regulation" . "ER calcium ion homeostasis" . "regulation of calcium ion concentration in endoplasmic reticulum" . "regulation of calcium ion concentration in ER" . "regulation of endoplasmic reticulum calcium ion concentration" . "regulation of ER calcium ion concentration" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .