Q-PCR analysis of insulin mRNA expression. Insulin expression in the five isolated K-cell clones (A) and the five isolated L-cell clones (B) was measured following exposure to low (L, 5 mM) or high (H, 25 mM) glucose. L-S1–L-S5: clones 1–5 exposed to low glucose. H-S1–H-S5: clones 1–5 exposed to high glucose. Gene expression was normalized for mouse β-actin and β-2 microglobulin (β2m) mRNA expression. Error bars indicate standard deviation.