A highly parallelized assay that allows simultaneous measurement of human endocrine cell composition, proliferation and protein levels. Islets were labeled with a total of 24 antibodies. The targets of these antibodies include the following groups: (1) markers of pancreatic subpopulations, such as C-PEPTIDE (beta cells), GLUCAGON (alpha cells), SOMATOSTATIN (delta cells), POLYPEPTIDE (PP cells), GASTRIN (GASTRIN cells), GHRELIN (epsilon cells), PDX1 (beta and delta cells), HNF1B (ductal cells) and CD49F (Integrin 6, acinar, ductal and subgroups of endocrine cells); (2) a replication marker, Ki67; (3) markers associated with beta-cell proliferation and metabolic activities, such as PDGFRA, pCREB, pERK1/2, pS6, pSTAT3, pSTAT5; (4) signaling pathway reporters, such as AXIN2 for WNT signaling, Cleaved-CASPASE3 (Cl-CASPASE3) for apoptosis, CPY26A1 for the retinoic acid pathway, and GATA2 for variability in chromatin accessibility; and (5) markers of beta-cell heterogeneity, such as CD9 and ST8SIA1. An iridium-containing DNA interchelator was used as a cell indicator and cisplatin as a viability marker. Data were analyzed using both traditional two-dimensional maps and multi-parametric analysis algorithms