In mutant embryos the division of neurons are affected in a lineage specific manner. The ganglion mother cell (GMC) of the RP2/sib lineage fails to divide, and assumes the identity of the RP2 neuron. The GMC of the aCC/pCC lineage is similarly affected; it fails to divide and assumes the identity of the aCC. These phenotypes are fully penetrant. Timing and axonal projections from these neurons continue as if they were wildtype. Other lineages are also affected in mutant embryos. The CQ lineage fails to divide in about 75% of hemisegments and the U lineage fails to divide in all hemisegments. The effect on the EL line is minimal.