To determine whether α cells expressed senescence markers at the protein level, we carried out immunohistochemistry for CDKN1A with GCG on age-matched ND donor and new, recent onset and established (0.58-8 years duration) T1D donor pancreas sections (n = 4 donors per group, Supplementary Table 1). The gene discussed is GCG; the disease is type 1 diabetes mellitus.