By using complementary screening approaches, a targeted tumour suppressor gene siRNA screen and a phopsho-RTK array, we have shown that loss of NF1 (neurofibromin) expression and increased activation and expression of both the HER2 receptor and the insulin receptor lead to resistance to saracatinib, via increased activation of the MAPK pathway (Figure 5). This evidence concerns the gene NF1 and neoplasm.