ITPR1 and intrahepatic cholangiocarcinoma: IRAG is phosphorylated by PKG1β at Ser696 and suppresses Ca2+ release from IP3R1 (Masuda et al., 2010; Schlossmann and Desch, 2011), and transcripts of the PKG1β splice variant (NM_ 011160) were 23-fold more abundant than transcripts of the PKG1α variant (NM_001013833) from RNA-seq of small intestinal ICC (Lee et al., 2017).