MYC and cancer: Whereas WT and Myc−/− cells expressed similar levels of the truncated α and β isoforms of Mlx, both of which localize to the cytoplasm because they lack GSMs at their N-termini [50], the latter markedly down-regulated the full-length γ-isoform, which does localize to the nucleus and is thus likely to be the transcriptionally active isoform [50,68,70]; 17 of the 33 different cancer types in The Cancer Genome Atlas also demonstrated significant direct correlations between Myc and Mlx transcript levels [50].