CD34 and acute lymphoblastic leukemia: In detail, T-ALL backbone panels are set up to evaluate both the asynchronous expression of classic T-cell maturation markers (namely, membrane/cytoplasmic CD3, CD5, CD7, CD2, CD4, CD8, CD34, CD45) and the ectopic expression of thymic antigens (such as CD99 and CD1a), as well as TdT, CD10, CD38 and CD56 [50,62,63].