levels at the roughened edge the roughened edge itself did not stimulate procollagen mrna synthesis as evidenced by the fact that cells located at the junction of the roughened edge and the natural edge of the circle where procollagen mrna synthesis has been shown to be low showed very low levels of procollagen mrna synthesis cells at the scraped edge continued to maintain high levels of procollagen mrna even though only half as many cells were in their immediate vicinity this is consistent with a factor being bound to the ecm that the cds is a loosely bound component of the ecm can be demonstrated by agitating the medium above the pat cell monolayer and monitoring the effects on collagen expression and cellular proliferation others have demonstrated that growth factors can be influenced by the laminar flow of the medium over cells in culture dunn g a amp g w ireland nature 1984 312 63 65 in observing the effects on collagen expression two conditions were used one where cells were seeded initially in a cloning ring and the second where the cells were seeded evenly over the whole plate the essential difference between these two conditions is in the ratio of medium volume to cell number the cell cultures were grown at 39 u00b0 c until confluent and then placed on a rocking platform for two days control plates were left unshaken the effect of agitation was dependent.