However, another study reports that expression of MUC1 protein and mRNA measured by western blotting and real-time PCR increases in the conjunctival epithelial cells gathered by impression cytology in the patients with Sjogren’s syndrome [31], suggesting further study is needed to uncover the mechanism of regulation of secretion of mucin components in dry eye-related ocular surface. Here, MUC5AC is linked to dry eye syndrome.