Activation of a mcf.2 oncogene by deletion of amino-terminal coding sequences

The mcf.2 transforming sequence was previously identified by tumorigenicity-assay of the mammary carcinoma cell line MCF-7, molecularly cloned and localized to Xq27 by in situ hybridization. cDNA clones representing both the activated gene and the corresponding portion of its normal counterpart were isolated and their nucleotide sequence determined. Sequence analysis showed that the mcf.2 gene was activated by rearrangement and loss of 5' sequences and no other alteration. Comparison of the mcf.2 nucleotide sequence with the recently published dbl sequence (Eva, A., G. Vecchio, D. Rao, S. Tronick & S. Aaronson (1988) Proc. Natl. Acad. Sci. USA, 85, 2061-2065) revealed that mcf.2 and dbl represent two different activated versions of the same proto-oncogene.