Isolation and characterization of mink lung epithelial cell mutants resistant to transforming growth factor β

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Abstract
Mink lung epithelial cells resistant to growth inhibition by transforming growth factor β (TGF-β) have been isolated by chemical mutagenesis and growth in the presence of platelet extracts enriched in TGF-β. Several resistant clones were isolated, at least one of which stably retained its resistance to TGF-β when grown in the absence of the factor. The cells of this clone were similar to the parent cells in morphology and growth properties. However, unlike the parent cells, the resistant cells did not show any of the following responses to TGF-β: (1) inhibition of DNA synthesis and proliferation; (2) morphological changes involving increased cell spreading; or (3) stimulation of synthesis of a 48-kilodalton secreted protein. The resistant cells do, however, retain a functional TGF-β receptor. The TGF-β resistant cell lines may be useful in genetic studies designed to identify the biochemical events required for inhibition of epithelial cell growth by this factor.