BCR and mantle cell lymphoma: In particular, PI3Kδ is found responsible for the B-cell receptor (BCR) signaling downstream transduction and constitutive studies show activation of BCR signaling pathway is a hallmark of B-cell malignancies such as chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), mantle cell lymphoma (MCL), small lymphocytic lymphoma (SLL), diffuse large B-cell lymphoma (DLBCL), and indolent non-Hodgkin’s lymphoma (iNHL).4