ITPR3 and cancer: Cancer cells express active σ1R that plays a crucial role in apoptosis by regulating [Ca2+] efflux across the ER and mitochondria after forming a complex with IP3R3 and anti-apoptotic proteins Bcl-2 and Ras-related C3 botulinum toxin substrate 1 (Rac1; Weng et al., 2017; Natsvlishvili et al., 2015).