PODN and Gliosis: Gliosis markers that were significantly decreased in Leprdb/db in comparison with samples from 24-week-old WT littermates included Gfap, Glul (encoding glutamine synthetase; also known as Gs), Vim (encoding vimentin), Egfr (encoding epidermal growth factor receptor), Ncan (encoding neurocan), Pcan, Timp2 (encoding tissue inhibitor of metalloproteinase 2) and Mmp14. At 6 weeks of age, the retinas of Leprdb/db mice had increased levels of Gfap, S100b (encoding S100 calcium-binding protein B), and Egfr, but these differences were not significant.