Soft agar growth assays for transforming growth factors and mitogenic peptides

Many different tumor cells produce and release transforming growth factors (TGFs) that influence the growth and behavior of the cells that produce them. Consequently, the production of TGFs may have important effects on the growth of tumors in vivo. The ability to grow in soft agar is one of the best indicators of a cell's tumorigenic capacity. TGFs can induce the soft agar growth of nontransformed cells. TGFs are usually assayed by their ability to induce the soft agar growth of nontransformed cells. This chapter describes methods to examine TGFs and related growth factors for their ability to influence anchorage-independent growth. The chapter discusses the most commonly used indicator cell lines, the general methodology employed, the selection of appropriate culture media, and a rapid assay that is suitable for testing small numbers of cells for the release of factors that influence anchorage-independent growth.