box 370 is a tight fitting box which is open at one end as two 1536 well plates 340 and 350 separated by an optional membrane 330 are inserted into the open end of box 370 they are forced together by the tight fit like a deck of cards being slid into its box alignment posts 361 and 362 are inserted through holes 371 and 372 in the box 370 as well as through matching holes in the membrane 330 and the plates 340 and 350 to insure proper alignment throughout centrifugation threaded ends of posts 361 and 362 may be utilized to attach assembly 300 to an appropriate centrifuge centrifugal force drives liquid from the wells in plates 350 which may be termed a source plate and into plate 340 which may be termed a target plate the optional membrane 330 may be used to perform a filtration or an adhesion step fig4 a and 4b show data from a transfer of labeled cells from a 1536 well plate to a polyvinylidine diflouride pvdf membrane in this experiment a column of empty wells was employed between each column of filled wells to make it easier to see if cross contamination had occurred chinese hamster ovary cho cells containing the interleukin 8 receptor subtype b il8b receptor were grown to a confluency in a standard.