GLP-1 secretion is dependent on Fpr-1 expression. A: Immunofluorescence labeling of GLP-1 in L cells of WT and Fpr1-KO HFD mouse colon sections (representative images; scale bars = 50 µm; 16 weeks on an HFD). B: Quantification of A, including NCD controls (n = 14–20/group). C: Proglucagon mRNA levels in the ileum of WT and Fpr1-KO mice, relative to WT NCD (n = 8, 16 weeks on an HFD). D: RNA fluorescence in situ hybridization of Proglucagon and Fpr1 in colonic L cells (representative images; scale bars = 10 µm) (n = 6/group). E and F: Glucose-stimulated GLP-1 secretion in mGLUTag cells treated with scrambled control siRNA (E) or Fpr1 siRNA (F) and different concentrations of fMLF (n = 5). Error bars indicate SEM. ns, not significant. *P < 0.05, **P < 0.001, ***P < 0.0001 by one-way ANOVA and Bonferroni post-test, comparing the indicated groups.