Excision of the P{EP} element in P{EP}MAPk-Ak2GE3296 results in deletion of sequences either side of the insertion site, which includes the second exon and part of the first exon of MAPk-Ak2.
Approximately 13% of MAPk-Ak2Δ12 mutant larvae exhibit a melanotic phenotype in response to strong salt stress (0.2M NaCl). A "black dot" is seen in the posterior hindgut and the affected hindgut epithelium appears pathologically altered. Very few mutants exhibit this phenotype when raised on food containing 0.1M NaCl or on normal food.
