In the LL/2 model we started the treatment at day 6 after tumor cell injection (Figure 9A). Here we observed that, blocking IL-9 at later time points during tumor development resulted in a significant tumor reduction as compared to IgG treatment (Figures 9B, C). pSTAT5 is activated downstream of IL-9 and thus we looked at pSTAT5 in lung CD4+CD25+ T cells and found that this cell population was down-regulated by anti-IL-9 antibody treatment (Figure 9D). By trend, we also found induction of IFN-ɣ after anti IL-9 treatment (Figure 9E). This evidence concerns the gene IL9 and neoplasm.