The effect of static pressure on the production of human granulocyte-macrophage colony stimulating factor (hGM-CSF) by the Chinese hamster ovary (CHO) cell line DR1000L4N was investigated. Although constant static pressures between 0.15 and 0.9 MPa had little influence on specific growth rate, the specific production rate of hGM-CSF increased from 1.23 to 1.62x10(-13) mg/cell/h in proportion to static pressure. The specific rate of tPA production by the human embryo lung cell line MRC-5 also increased from 2.92 to 6.38 x 10(-12) mg/cell/h as static pressure increased. The expression level of hGM-CSF mRNA increased with the pressurization even for 4 h.