Recently, researchers from stanford university have changed mouse skin cells into mouse nerve cells. this was accomplished by inserting genes that control the synthesis of certain proteins into the skin cells. this type of research is often successful in advancing knowledge regarding the functioning of human cells because
(1)cells present in humans often function in similar ways to cells present in other organisms
(2)cells from different types of organisms function differently when transplanted into humans
(3)the cells in all complex organisms contain the same genes and function in similar ways
(4)cellular research using mice can always be applied to human cells since all complex organisms produce the same proteins