the factor ( s ) is produced also by bhk21 cells transformed by other tumor viruses and by bhk21 cells passaged for a long time , but not by normal cef , cef transformed by b-rsv , cef infected by fu-19 at 41 degrees c , normal hamster embryo fibroblasts , established but density-inhibited mouse fibroblasts , or bhk21 cells of early passages .
C0016030
fibroblasts
C0007634
cells