with the SpectraCube system and analyzed with SKYview imaging software. Results: The average number of chromosomes was 84 in Caco-2, 73 in Colo-205, 62 in SW403, 46 in HCT-15, 45 in HCT-116, and 49 in Lovo. We found 11 structural alterations in Caco-2, 9 in Colo-205, 6 in SW403, 1 in HCT-15, 2 in HCT-116, and 2 in Lovo. The aberrations in NonRER colon cancer cells include complex rearrangements, such as der(13)t(13;6;13) in Colo-205, that have net been identified by conventional banding techniques. Most of the alterations in NonRER colon cancer cells were imbalanced, resulting in chromosomal gains and losses. Discussion: SKY enabled a detailed analysis of structural alterations, generating a complete karyotype. In comparison to NonRER-cells, RER-cells show a strikingly lower incidence of chromosomal gains and losses. Additionally, RER colon cancer cells displayed a markedly lower incidence of structural and numerical chromosomal alterations. Further studies have to show if the simple translocation pattern in RER colon tumors may be used for tumor classification and for prediction of therapeutic responses.