RRM2 and dry eye syndrome: Genes down-regulated by TNF-α in KCs (FDR < 0.10) but up-regulated by IDL, IDC and IDL + IDC included ribonucleotide reductase M2 polypeptide (RRM2), DNA topoisomerase II alpha (TOP2A), and denticleless E3 ubiquitin protein ligase homolog (DTL) (Figure 4J).