Fig. 7. RHG-motif genes involved in the apoptosis of pioneer neurons. (A) Organization of the genomic region containing four of the five known RHG-motif cell death activators in Drosophila. The H99 deletion removes hid, grim and rpr. skl resides proximal to rpr, just outside the H99 region. XR38 removes rpr and, perhaps, skl. X14 removes hid only, while X25 removes hid and grim (based upon Peterson et al., 2002). (B) Effect of different mutant combinations, removing one or more of the RHG-motif genes, on the survival of anterior dMP2 (black bars) and MP1 (grey bars) neurons. The vertical axis shows the number of surviving anterior pioneer neurons in late embryos (air-filled trachea stage) for each genotype (n>7 VNCs). See text for details.