AQP3 and diabetes mellitus: Recently, research has clarified that the AQP3 level in the skin decreases when the skin dries due to psoriasis [22], vitiligo [23,24], diabetes mellitus [25], aging [26], etc. We previously confirmed that the dry skin that occurs with the administration of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors as anticancer agents is associated with decreased AQP3 levels in the skin [27].