ITPR1 and colorectal cancer: We conclude that KRAP, originally identified because it is upregulated in colorectal cancer cell lines expressing mutant KRas (Inokuchi et al., 2004), fulfils a dual function in regulating Ca2+ transfer from the ER to mitochondria through IP3Rs. KRAP licenses IP3R within ERMCSs to respond to IP3, just as it does for IP3Rs that release Ca2+ to the cytosol (Thillaiappan et al., 2021).