sentence: In the course of evolution , some of the yeast SWI / SNF subunits stayed conserved in mammalian genes encoding the BAF complex subunits BAF250a / b ( homologues of Swi1 ) , BRG1 / BRM ( Swi2 ) , BAF155 / 170 ( Swi3 ) , BAF60 ( Swp73 ) , BAF53 ( ARP7 / 9 ) , BAF47 ( Snf5 ) and the BAF45 family ( Swp 82 ) .