Of particular interest, however, was our observation that certain signalling cascades, including those mediated by Igf1 and Vegf, were differentially activated by cluster 1 and cluster 2 K-Ras mutants, suggesting that not only the presence but the specific molecular characteristics of individual K-Ras mutations may be important determinants of both tumour progression and treatment response. Here, IGF1 is linked to neoplasm.