DIDO1 and RBM39 protein expression was quite strong in the majority of tumors irrespective of 20q DNA copy number status.<h4>Conclusion</h4>The lack of correlation between protein expression levels and 20q DNA copy number status implies that CSE1L, DIDO1 and RBM39 are merely passengers rather than drivers of chromosome 20q gain in colorectal adenoma-to-carcinoma progression. Here, DIDO1 is linked to colorectal adenoma.