[Serum-free culture of tumor cells--recent problems in autocrine hypothesis]

Tumor cell lines in culture that can grow in protein-free medium are suitable for studying the mechanism of autonomous growth of tumor cells. We have studied the mechanism of autonomous growth of three cell lines which were established from human solid tumors. These cell lines produce basic fibroblast growth factor (bFGF), but it does not seem to act as an autocrine growth factor. bFGF produced by these cells is accumulated in the nuclei and may act as an autointrafactor for autonomous growth of these cells.