Cumulative effect of pressure on synthesis of RANK by cultured human macrophages. Macrophages were cultured at 5 × 105/well for 7 days. 1,25D3 (10-7M or 10-9M) was added and cultures were subjected to four cycles of pressure (34.5 × 10-3MPa). Macrophages were immunostained for RANK with a specific polyclonal antibody. Cells exposed to pressure and 10-7M 1,25D3 (a) synthesised more RANK than cells exposed to pressure and 10-9M 1,25D3 (b). Cultures supplemented with 1,25D3 synthesised more RANK than control cultures without 1,25D3 (c). Pressurised MP synthesised more RANK than control cultures without pressure (d). In unpressurized cultures, MP synthesis of RANK again varied with the stimulus; 10-7M 1,25D3 (e); 10-9M 1,25D3 (f); no 1,25D3 (g).