Remobilization of the chimeric progenitor P-element (P{XP-U}FASN^Δ24) present in Df(2L)FASN^Δ24, resulting in an imprecise excision that removes an addition 1200bp of the FASN1 gene, including the first methionine codon and the sequence coding half of the KS domain. FASN2 expression is not detected and FASN1 transcript levels are barely detectable.

Lethal at the L1 larval stage. Lethality can be partially rescued by growing flies on a low carbohydrate diet supplemented with butter and egg yolk (as dietary lipid sources); addition of 10% sucrose to this diet results in total lethality at L1 stage.

For larvae fed a low carbohydrate diet, the size of cells in Df(2L)FASN^Δ24-23 clones is slightly reduced compare to neighboring control cells. However, as the sucrose content in the diet increases, a concomitant reduction in the size of cells is observed.