In Part B additional patients with AML will be treated to further characterize the tolerability,biological effects, and clinical efficacy of the combination Velcade plus Zarnestra. Patients on treatment for AML will undergo regular bone marrow aspirates and biopsies to assess responses to treatment. This will facilitate frequent assessment of biological endpoints (reduction in expression and phosphorylation of IKKb kinase, and downstream markers of signalling along with apoptosis, survival, proliferation and cellular size and ploidy) will be made in an attempt to confirm that the desired biological activity has been achieved at the maximum tolerated dose.