The oncogenic activity of c-MYC is well known, and genetic aberrations
in this locus are associated with a variety of human neoplasms. Becau
se the encoded MYC protein has transcriptional activity only when dime
rized with MAX, it is possible that mutations of MAX also could have p
henotypic consequences. We have now found, by fluorescence in situ hyb
ridization and quantified Southern blot analyses, that the MAX gene ha
s been reduced to hemizygosity in HL60 cells. Although the sequence of
the coding region of the remaining allele of the MAX gene is not muta
ted, this reduction in gene dosage may be the cause of a lower abundan
ce of MAX protein in these cells that could result in an imbalance in
the complex transcription factor network in which MAX has a pivotal ro
le. (C) Elsevier Science Inc., 1998.