We used semi-quantitative reverse-transcriptase PCR (RT-PCR) and Western blot to investigate the expression of full length p53 (TAp53), Delta40p53, Delta133p53 or p53beta in diagnostic marrow from a clinical cohort of 50 BCP-ALL patients without TP53 mutation (29 males and 21 females, age range 2–14 years) and in the bone marrow cells of 4 healthy donors (used as controls). The gene discussed is TP53; the disease is acute lymphoblastic leukemia.