Enhancer trap staining was investigated in the lamina precursor cells (LPCs) in third instar larval brains. The highest level of staining occurs in LPCs along the anterior segment of the lamina furrow in cells that are in the G₂ and M phase of the first division. Expression is also seen in the inner optic anlage and in some cells of the central brain. Expression also occurs in the antenna, eye, leg, and wing discs and in embryos.