Crossing four transgenic lines containing U2af50D204N.ts with U2af50XR15 heterozygotes results in rescue of the U2af50XR15 phenotype in two of the lines (P{U2af50.D204N.ts}1 and P{U2af50.D204N.ts}4), with an optimal rescue of 39% at 25oC and 15% at 29oC in one of the lines (P{U2af50.D204N.ts}1).