(A) Schematic diagram depicting Cre-mediated activation of GluR-B(Q) by removing the loxP-flanked TK-neo (TK-neo pA, GluR-Bneo) element in intron 11, which is acting as a suppressor in expression from the Q/R site editing deficient GluR-Bneo allele. Exon 10 and 11 encode membrane-spanning segments 1, 2, and 3 (M1, 2, 3) of the GluR-B subunit. The intronic element necessary for editing the Q/R site is shown for the wild-type allele (+).