The targeting vector introduced into the locus a floxed neomycin resistance/STOP cassette, tetracycline-regulated transcription activator (tTA), insulator, hCMV*1 promoter, intron, fusion of human KIAA1549 (exons 1 to 16) and BRAF (exons 9 to 18) (KIAA:BRAF 16_9), IRES and EGFP. This fusion was found in pilocytic astrocytomas of young children.