TP53 and B-cell chronic lymphocytic leukemia: In another study by Zenz et al., miR-34a was downregulated in fludarabine-resistant CLL cells in a p53 defective pathway manner [118]. However, in Ferracin’s study, no difference in miR-34a expression was found between non-responders and responders, but it was noted that in three patients known to have del17p, miR-34 expression could not be detected [117].