Consistent with this possibility, α3(V)-free ECM from KO/PyMT tumour cells (Fig. 7i) and ECM of WT/PyMT tumour cells in which GPC1 had been knocked down (Fig. 7i) both contained less FGF2 than did control WT/PyMT tumour cell ECM. The gene discussed is GPC1; the disease is neoplasm.