複選題38. About Lisa's analysis of the fly mutant, which of the following are correct? (A) The axon defects that Lisa identified represent loss-of-function phenotypes of the small GTPase (B) The mutation that Lisa identified could be a gain-of-function mutation of the small GTPase (C) The small GTPase normally is not required for axon projection of the eye (D) There is possibility that an unrelated background mutation, which is somehow linked to the small GTPase mutation, actually causes the axon defects (E) The gene is essential for embryonic development