α-MSH, however, did induce a modest and significant up-regulation in the ratio of p-Erk1 or 2 over total Erk1 or 2 in the dry eye group relative to the saline controls (Fig. 7B,D, p < 0.05, D+ α-MSH vs NaCl+NaCl), and this up-regulation was significantly suppressed by PD98059, but not by H89 and DMSO. This evidence concerns the gene MAPK3 and dry eye syndrome.