Figure 1
From: Endoplasmic reticulum Ca2+-homeostasis is altered in small and non-small cell lung cancer cell lines
Increase in the cytoplasmic Ca2+-concentration can be due to Ca2+-influx from the extracellular space or due to Ca2+-release from the endoplasmic reticulum (ER). The equilibrium of the ER Ca2+-content is maintained by sarcoplasmic/endoplasmic reticulum Ca2+-ATPases (SERCA) pumping calcium into the ER and inositol-1,4,5-phosphate- (IP3R) and ryanodine-receptors (RYR) releasing calcium out of the ER. Within the ER, calcium is mainly buffered by calreticulin.