IL13RA2 and melanoma: Thus, in accord with the findings by Strober et al. and prior studies that demonstrate that the levels of circulating Chi3l1/YKL-40 are increased in patients with advanced melanoma (Schmidt et al., 2006), an IL-13-Chi3l1/YKL-40-IL-13Rα2-TGF-β1 axis appears to play a critical role in the progression of malignant melanoma.