MUC1 and Keratoconjunctivitis sicca: However, several consistent findings were found, including reports by Argüeso et al. [22] and Caffery et al. [20,21], who reported no or few differences in the expression of MUC1, MUC4, or MUC16 mRNA or protein expression between keratoconjunctivitis sicca (KCS) and control groups.