JWA is a four-transmembrane environmental responsive protein which binds to the CC chemokine recepor 5 (CCR5), a major co-receptor for human immunodeficiency virus (HIV). JWA is involved in environmental stress-responsive pathways in K562 cells, an erythroleukemia cell line derived from patients with chronic myeloid leukemia. Environmental stressors to K562 cells such as heat shock, a higher temperature than the ideal body temperature of the organism from which the cell line was derived, and oxidative stress, the production of oxygen-centered free radicals, regulate and increase the expres-sion of JWA. This response to environmental stressors suggests similiarity of JWA to heat shock protein 70 (HSP70), which is upregulated by heat stress and toxic chemicals.