Slob-null and RNAi flies show reduced Slob protein expression in adult fly heads. (A) In mut^IP1 flies (lane 2), there is greatly reduced Slob expression compared with the WT^P41 line (lane 1). The remaining staining near 57 kD in lane 2 is a result of the presence of a cross-reacting band not related to Slob. Slob expression driven by a ubiquitous (lane 3) or nervous system–specific elav-GS (lane 4) Gal4 driver in the mut^IP1 background is able to restore Slob expression in the fly head. (B) In Slob-RNAi flies, expression of Slob-RNAi driven by the ubiquitous Gal4 driver reduces the expression of Slob protein (lane 2). In contrast, Slob-RNAi expression driven by either the muscle-specific Gal4 driver (lane 3) or the nerve-specific Gal4 driver 1407-Gal4 (lane 4) does not affect Slob levels in the adult head. WT¹ and WT² are the uncrossed parental lines used as WT controls (refer to Materials and methods); WT³ is a yellow-white fly line used as an additional control.