IL13 and neoplasm: Puri and colleagues [31], [32] have previously shown that tumor cells expressing IL-13Rα2 are susceptible to the cytotoxic effects of IL13-PE making this chimeric protein a highly effective anti-tumor agent, and we have extended these findings to show that targeting IL-13 responsive cells such as fibroblasts is also highly effective in treating established fibrotic responses in the lung [24].