Rabbit anti activated caspase 3

We followed the immunostaining protocol that was previously described by Liu et al. (99 (link)). Briefly, we incubated the samples in blocking solution [0.3% Triton X-100 and 4% bovine serum albumin (BSA) in PBS] at room temperature for at least 1 hour, followed by overnight incubation with primary antibodies at 4°C. After removing the primary antibodies, we washed the samples using washing buffer (0.3% Triton X-100 in PBS) at least 10 times at room temperature. Next, we incubated the samples in blocking solution with fluorescent dye–conjugated secondary antibodies and the nuclear counterstain 4′,6-diamidino-2-phenylindole (DAPI) (Thermo Fisher Scientific) at 4°C overnight. On the following day, we removed the solution and washed the samples with washing buffer 10 times at room temperature. The following primary antibodies were used: chicken anti-GFP (1:500; Aves Labs, GFP-1020), goat anti-tdTomato (1:500; MyBioSource, MBS448092), rabbit anti-insulin (1:100; Cambridge Research Biochemicals, customized), mouse anti-glucagon (1:50; Sigma-Aldrich, G2654), rat anti-Sst1.1 (1:50; GeneTex, GTX39061), rabbit anti-Cdh17 (1:1000; customized sera, gift from Y. Cao, Tongji University), rabbit anti-Cldnc (1:200; customized sera, gift from Y. Cao, Tongji University), rabbit anti-Vasnb (1:1000; customized sera, gift from P. Panza), and rabbit anti-activated Caspase-3 (1:100; Chemicon).