chick embryo fibroblasts ( cef ) and hamster bhk21 cells transformed by the schmidt-ruppin strain of rous sarcoma virus ( sr-rsv ) release into the culture medium a factor or factors which enhance 2- to 7-fold the formation of transformed foci by chich embryo fibroblasts infected with the bryan strain of rsv ( b-rsv ) .
C0007634
cells
C0016030
fibroblasts