A previous publication (Leith et al., 1992) showed that administration of basic fibroblast growth factor (FGF-2, 0.25 mg kg-1, q.i.d. x 7) to mice bearing xenografted DLD-2 human colon cancers would increase treated tumour growth rates as compared to control neoplasms. The gene discussed is FGF2; the disease is neoplasm.