Fig. 7.

β8 integrin promotes NPC proliferation and self-renewal in vitro. (A,B) Neural progenitors were cultured from the SVZs of P60 wild-type (A) and β8^–/– (B) adult mice. NPCs proliferate to form free-floating neurospheres in serum-free medium containing EGF and bFGF. (C) Diameters of 300 randomly selected neurospheres from P60 wild-type mice (n=3) or β8^–/– mice (n=3) were measured. Note the reduced diameters of β8^–/– neurospheres, *P=0.0006 compared with wild-type neurospheres. (D) Detergent-soluble protein lysates from wild-type or β8^–/– neurospheres were immunoblotted with anti-αv and -β8 integrin polyclonal antibodies, or anti-actin to control for protein loading. (E) A proliferation and self-renewal assay in which individual neurospheres from each of two wild-type and two β8^–/– mice (n=12 neurospheres per genotype) were physically dissociated and the total numbers of newly formed spheres were quantified over seven sequential passages. Note the progressive reduction in new sphere formation in cells genetically null for β8 integrin, *P<0.001 for passage two to passage seven compared with wild-type neurospheres.