TAPP2 regulates cell adhesion to extracellular matrix proteins. BJAB cells were incubated in fibronectin- or laminin-coated wells under the indicated conditions. After 1 hour nonadhered cells were removed, and then plates were fixed and stained with crystal violet. Stained cells were dissolved in SDS buffer and the optical density at 570 nm was read on an absorbance plate reader. (A) BCR cross-linking induces a PI3K-dependent increase in B-lymphoma cell adhesion to laminin and fibronectin. (Right bars) BJAB cells were stimulated with increasing doses of anti-BCR or in medium alone during the 1-hour adhesion assay. The triangle indicates increasing concentrations of anti-BCR stimulus (0.01, 0.1, 1, or 10 μg/mL). (Left bars) Cells were stimulated with 10 μg/mL anti-BCR during adhesion assay together with addition of PI3K inhibitors or DMSO diluent containing no inhibitor (DMSO indicates 0.5% DMSO with no inhibitor; LY29, 50μM LY294002; Wort, 50 nM wortmannin; and IC87, 50μM IC87114). (B) BJAB transfectants expressing the indicated TAPP2 proteins were assessed for BCR-induced adhesion (Control indicates untransfected BJAB; WT, BJAB expressing wild-type TAPP2; Myr, expressing myristoylated TAPP2; and R218L, expressing PH mutant TAPP2). Anti–BCR-lo denotes stimulation with 0.1 μg/mL concentration, whereas anti–BCR-hi denotes stimulation with 1 μg/mL. Note that at 0.1-μg/mL dose, all TAPP2 transfectants showed significantly altered adhesion compared with control BJAB cells (**P < .05 by Student t test). Results shown represent average and SE obtained from 3 to 5 independent experiments, and are representative of data obtained with at least 2 independent stable transfectants.