Gsk3b^tm1Grc

A mutant FRB tag, composed of an 89 amino acids with three point mutations (K2095P, T2098L, and W2101F), was targeted into the C terminus of the locus. A floxed neo cassette was inserted into the last intron and an FRB*HA sequence placed immediately before the stop codon. The neo was subsequently removed via crossing with mice expressing cre recombinase in the germline. Presence of this mutant FRB tag destabilizes the protein resulting in decrease or loss of expression. Addition of rapamycin or a rapamycin analogue stabilizes the protein and restores expression. (J:100153)