Cao et al. (2011) extracted RNA from non-AMD and AMD tissue samples and compared CXCL11 (secreted from M1 macrophages) and CCL22 (from M2 macrophages) expression levels to determine the presence and ratio of M1 and M2 macrophages in the macular choroid. The gene discussed is CCL22; the disease is age-related macular degeneration.