Epidermal growth factor-nonresponsive 3T3 variants do not contain epidermal growth factor receptor-related antigens...

We have previously isolated three independent variants of Swiss 3T3 cells that are unable to generate a mitogenic response to epidermal growth factor (EGF). Each of the variants is unable to bind 125I-labeled EGF; each lacks a functional EGF receptor. We used an antiserum to murine EGF receptor to look for an EGF-receptor gene product in wild-type 3T3 cells and in the three EGF-nonresponsive variants. No cross-reactive material could be detected in any of the three variants, either in 125I-labeled cell extracts or in [35S]methionine metabolically labeled cells. 3T3 cells contained mRNA molecules homologous to a cDNA probe for the human EGF-receptor coding region. In contrast, no homologous RNA could be detected in any of the three variants. Analysis of genomic Southern blots of the DNA from 3T3 cells and the three EGF-nonresponsive variants indicated sequences from the EGF-receptor gene are present in the DNA of all four cell lines. These EGF-nonresponsive lines, which demonstrate proliferative responses to a variety of mitogens, will be ideal recipients for structure-function studies of the EGF receptor by transfection of the cloned gene.