Deregulated miR component of the p53 pathway in refractory CLL. The expression of miR-34a in CLL is tightly linked to the presence of TP53 mutations or 17p deletion, but also to refractory disease. When separating subgroups based on the presence of TP53 mutation or 17p deletion, all subgroups with TP53 alteration show strikingly similar miR-34a expression. In cases with F-refractory CLL (without TP53 mutation or 17p−), miR-34a levels are on average higher, but a subset of cases show expression levels similar to TP53 mutation/17p− cases. Bar represents mean expression.