The N-terminal 24 aa (exon 1) of Ppp2r2b have been replaced with the coding sequence for beta-gal (lacZ) and a neomycin cassette surrounded by two loxP sites followed by a polyadenylation signal to terminate the transcript. A correctly targeted mouse was crossed with a Cre deleter mouse to remove the neomycin cassette. The allele is a null allele. Loss of protain product was confirmed by Western blotting PP2A holoenzymes purified from total forebrain. (J:290154)