For example, deficiency of CXCR5 causes defects in RPE cells and an AMD-like phenotype in CXCR5 knockout mice, and transcriptome analysis of primary RPE cells from these mice highlights the PI3K-Akt and mTOR signaling pathways as important for RPE homeostasis [66]. Here, CXCR5 is linked to age-related macular degeneration.