As shown in Figure 3A, the parent peptide tigerinin-1R exhibited insulin-releasing activity in rat insulinoma INS-1 cells after incubation for 1 h in 1 mL KRB buffer (115 mM NaCl, 4.7 mM KCl, 1.28 mM CaCl2, 1.2 mM KH2PO4, 1.2 mM MgSO4, 10 mM NaHCO3, and 1 g/L BSA, pH 7.4) at 37 °C. Here, INS is linked to pancreatic insulinoma.