CD9 and acute lymphoblastic leukemia: Interestingly, previous studies demonstrated that B-cell malignancies result from abnormal dysregulation of B-cell–activating factor (BAFF) (Li et al., 2021) and the PI3K-Akt signaling pathway in B-lineage ALL is activated through the interaction of PI3K-p85 and CD9 (Shi et al., 2021).