cmb^KO is a protein null mutant.

(A) Genomic locus of cmb/CG10732 showing the RA and RB isoforms that are well supported by genomic data. 1023 bp of genomic DNA (red) was replaced with a White⁺ marker by homologous recombination to generate the cmb^KO allele. The deleted fragment includes the start codon of the PB isoform. Arrows indicate approximate location of the PCR primers used to verify the deletion. (B) Analytical PCR shows that cmb specific primers amplify a 945 bp fragment from w¹¹¹⁸ control DNA (lane 2), but not from homozygous cmb^KO DNA (lane 1). Control primers amplify the expected 532 bp fragment from both DNAs showing their integrity (lanes 4, 5). Lanes 3, 6: No DNA controls. (C) Western blot analysis of 3^rd instar larval lysates separated on a 12% SDS-PA gel shows that, in contrast to a w¹¹¹⁸ lysate (left lane), neither Cmb-PA nor Cmb-PB (arrows; predicted MWs 189 kDa and 89 kDa, respectively) are detected in lysates of homozygous cmb^KO flies. The minor form running above Cmb-PB may be a modified form and was not detected in all preparations. αTubulin was used as loading control (lower panel). (D–F) Wing hairs and their orientation of cmb^KO flies are normal. Compare enlarged wing area of a w¹¹¹⁸ wing (E) with a cmb^KO wing in (F; area corresponds to blue box in D). Scale bar is 50 µm.