SSTR2 and ileal neuroendocrine tumor G1: Accordingly, in a SRIFoma, which synthesized and secreted SRIF and in which SST2 are localized intracellularly, receptors are phosphorylated, whereas in an ileal carcinoid tumor in which SST2 are membrane-bound, receptors are found nonphosphorylated (Liu et al., 2003).