OPN1SW and precursor B-cell acute lymphoblastic leukemia: The expression of functional BAFF-system receptors by B-ALL was unexpected since their physiological expression seemed restricted to later B-cell lineage developmental stages.[28] We confirmed the lack of BCMA, TACI and BAFF-R proteins in normal BCP despite detection of their respective transcripts, suggesting post-transcriptional regulation of receptor expression in early B-cell development.