A floxed neo cassette replaced most of the coding region in exon 1 and exons 2 and 3. These exons code for the SAM domain and 3 phosphotyrosine motifs. Two amino acids (Ser and Arg) were added to the modified exon 1 to prevent a frame shift. Germ line, cre mediated recombination removed the neo cassette. (J:150304)