CXCR7 mediates neural progenitor cell (NPC) migration in response to CXCL12 in vitro. (A–I): Wild type and Cxcr4 knock out NPCs were seeded on bovine serum albumin (BSA) stripes (A–D) and BSA/CXCL12 stripes (E–H). Cells were stained with nestin (purple) and counted after 48 hours. Scale bar =60 μm (A–H). The quantification of Stripe Assay is shown in (I). (J): NPCs on transwell inserts were incubated under the indicated conditions in the presence of CXCL12 and other agents as indicated. *, p <0.05, **, p <0.01, ***, p <0.001, compared with the untreated control of the same cell type; #, p <0.001; NS, nonsignificant. Abbreviation: BSA, bovine serum albumin.