We mimicked the BM microenvironment using the culture media containing the pre-established monolayer of HS-5 BMSCs or C-X-C motif chemokine ligand 12 (CXCL12)-enriched complete media in the lower well; meanwhile, we activated CD28- and/or CD40LG-signaling of BACH2OE T-ALL cells with anti-human CD28 activating monoclonal antibodies (hCD28-mAb) and/or recombinant human CD40 proteins (rhCD40) in the upper chamber (Fig. 7C). Here, CD28 is linked to acute lymphoblastic leukemia.