F2RL1 and type 1 diabetes mellitus: In contrast to the mouse, where a small number of α-cells had high PAR2 expression, consistent with the very low but detectable level of transdifferentiation with β-cell ablation alone seen by us 5 and others;29 in normal or T1D patients there were no normal α-cells with high PAR2 expression, suggesting that PAR2 regulation is more stringent in humans than in mice.