Although HSP70 and HSC70 do not contain export signal peptide sequences, and more importantly depend in their chaperone function on repetitive cycles of ATP hydrolysis, they are found on the cell surface of a number of different cell types including tumor cells, virus infected cells, spermatogenic cells, epidermal cells, arterial smooth muscle cells, monocytes and B cells [49]. The gene discussed is HSPA8; the disease is neoplasm.