Thymic stromal lymphopoietin (TSLP), a pro-Th2 cytokine predominantly expressed by epithelial cells and keratinocytes, was initially recognized in driving pathogenesis of atopic diseases, including atopic dermatitis, asthma, and allergic march (5, 6), and it has been recently implicated in various types of tumors (7). This evidence concerns the gene TSLP and asthma.