CD81 and precursor B-cell acute lymphoblastic leukemia: In particular, a recent multicentric EuroFlow study [36] has demonstrated that a fully standardized bulk lysis protocol with two stepwise designed 8-color tubes (including the BCP backbone panel plus CD81, and either CD66c/CD123 or CD73/CD304, combined in the PE fluorescence channel of each tube) allows highly sensitive MRD measurements (up to 10−5, comparable to PCR method, with >90% concordance) in virtually all B-ALL patients (>98%), as long as large numbers of events are acquired (>4 million BM cells).