Exposure to serum alone (in the presence of 15% foetal calf serum) or integrin-mediated adhesion (serum-free monolayer cultures on a collagen matrix), both rendered one of the four Ewing tumour cell lines at least partially resistant to 5 ng ml−1 FGF-2 (serum in RD-ES and adhesion in RM-82; Figure 3A and B). This evidence concerns the gene FGF2 and Ewing sarcoma.