Fig. 3. The expression of Hox proteins in the VNC is mainly neuronal, and only Abd-B parallels the segmental survival of dMP2 neurons. (A-D) Hox gene expression at embryonic stage 16 in a subset of embryonic postmitotic neurons (UAS-nls-myc-EGFP/+; HB9-GAL4/UAS-nls-myc-EGFP). Within a Hox expression domain, most neurons express the relevant Hox gene (arrows). However, a few do not (arrowheads). (E-L) Hox proteins are largely absent from midline (E-H) and lateral (I-L) glial cells at the same stage, with a few exceptions (L, arrow). (M-P) Only the Abd-B expression profile fits the dMP2 survival/death boundary: neither Antp (M) nor Ubx (N) is present in A5 or A6, Abd-A is expressed in both (O) and only Abd-B is expressed in A6, but not in A5 (P). (Q) Diagram summarizing the expression of Hox genes in the VNC (left) and in dMP2 neurons (circles). Hox gene expression within a specific cell type, in this case the dMP2 neurons, cannot necessarily be inferred from the general Hox expression domain boundaries in the VNC. At stage 16, Abd-B is specifically expressed in dMP2 neurons that will survive into larval stages.