SST1 transduces reduction of both cAMP accumulation and intracellular Ca2+ concentrations in heterologous cell systems (Fig. 4) (Garcia and Myers, 1994; Hadcock et al., 1994; Hershberger et al., 1994; Patel et al., 1994), as well as in insulinoma cells expressing SST1 endogenously (Roosterman et al., 1998). This evidence concerns the gene SSTR1 and pancreatic insulinoma.