Fig 1: Static insulin and serotonin secretion assays in INS 832/13 rat insulinoma cells: (A) Supernatant insulin secretion in low (2.8 mM) and high (16.7 mM) glucose conditions following treatment with BMP6 (100 ng/mL) (n = 8) was measured with ELISA, while (B) relative mRNA expression of glucose metabolism-related genes was measured in cell lysate with RT-qPCR (n = 12). (C) Supernatant insulin secretion in low (2.8 mM) and high (16.7 mM) glucose conditions following treatment with 5HT (1 µM and 10 µM) (n = 6) was measured with ELISA, while (D) relative mRNA expression of glucose metabolism-related genes was measured in cell lysate with RT-qPCR (n = 4). (E) Supernatant serotonin secretion with increasing glucose concentrations (0 mM, 8.3 mM and 16.7 mM) following the treatment with BMP6 (100 ng/mL) was measured with ELISA (n = 6), while (F) relative mRNA expression of serotonin metabolism-related genes was measured in cell lysates with RT-qPCR (n = 8). Results of relative mRNA expression are reported as fold change + SEM, while ELISA results are reported as mean + SEM. * p < 0.05, ** p < 0.01, *** p < 0.001.