The sgg-PD tag also tags sgg-PP and sgg-PQ. The sgg-PD isoform shows early expression that is largely restricted to mesoderm and becomes more prominent at stage 9 . At later stages the expression of sgg-PD is generally weak and ubiquitous with elevated levels found in the CNS, posterior spiracles, Malpighian tubules, proventriculus and salivary glands.