CXCL12 and age-related macular degeneration: Interestingly, obstruction of CXCR4 signal transduction by AMD markedly increased CXCR4+/nestin− cells population (control, 1.8 ± 0.3%; AMD, 7.3 ± 1.3%, p < 0.05) implying that SDF-1/CXCR4 cascades may contribute to the sustaining characteristics of NSCs/NPCs.