However, immunohistochemical positivity of cyclin A, cyclin B, cyclin D1, cyclin E and cdc2 [17,19,20] or the loss of cyclin kinase inhibitors p27 and p21 [16-18,25-27] has only been shown to be associated with high risk grading in GIST, while investigations in regard to clinical outcome are missing. This evidence concerns the gene CDK1 and gastrointestinal stromal tumor.