To further characterise the cellular components of the tumour bulk, we analysed the number of α-SMA-positive fibroblasts and pan-cytokeratin-positive tumour cells in n=25 untreated KPC mice and found around three times more tumour cells (mean number 122/high power fields (HPF)) compared with fibroblasts (mean number 44/HPF, p<0.0001) (see online supplementary figure S7A, B). Here, ACTA1 is linked to neoplasm.