However, loss of function experiments conducted with shRNAs specific for IL-8 vs. IL-6 demonstrated that IL-8 is involved in the resistance of the tumor cells to erlotinib, as silencing of IL-8 (but not IL-6) was able to reconstitute sensitivity to erlotinib to the level observed with parental cancer cells. This evidence concerns the gene CXCL8 and neoplasm.