Selected DEGs that exhibited higher islet expression in T2D, i.e., BARX1, ELFN1, FAIM2, NEFL, PAX5, PCOLCE2, and SFRP1 (Figure 4C), were overexpressed by plasmid transfection in 832/13 INS1 β cells (hereafter called INS1 β cells). The gene discussed is PCOLCE2; the disease is type 2 diabetes mellitus.