Exon 10 was replaced with one containing a point mutation resulting in a tyrosine to phenylalanine change at amino acid 416 (Y416F) and exon 11 was flanked by loxP sites. In addition, a neomycin resistance cassette flanked by FRT sites was inserted upstream of exon 11. Flp-mediated recombination removed the neo cassette. Cre-mediated recombination deleted exon 11 and abrogates STAT and ERK signaling and leads to a shortened intracellular domain with 14 alternative amino acids coded by the former intron 11 until translation is stopped by a new stop codon. (J:268135)