When males with Dp(1;1)Co are crossed with T(1;2)scS2 females, and somatic clones are induced (in the wing disc) with a FRT site at 18A, clones with cells containing 4 copies of dm (2 endogenous and 2 from the tandem duplication in Dp(1;1)Co) and heterozygous for RpL19 (due to missing one copy of RpL19 on Ts(1Lt;2Lt)scS2). These clones are unable to out-compete surrounding cells and are eliminated.