The mutation of Dally is a consequence of the P-element and the place where it is located. It is possible to differentiate between the mutants Dally-P1 and Dally-P2, depending on where the insertion of P-element is. It is known that Dally-P2 generates a bigger amount of defects. This mutated Dally disrupts the cell cycle progression, delaying the process during the G2-mitosis transition. As a matter of fact, mutations affecting Dally disrupt patterning of many tissues, for instance of the nervous system.  Dally mutants display cell cycle progression defects in specific sets of dividing cells. Those mutations are pleiotropic and can affect viability and produce morphological defects in several adult tissues, such as the eye, antenna, wing and genitalia.