UASp regulatory sequences control expression of a 3.6kb genomic fragment that contains the Lkb1 transcription unit, mutated to contain a modification (C537A) that is intended to prevent prenylation of Lkb1 in vivo, by mutating a putative prenyl-acceptor cysteine to alanine. A GFP tag has been inserted at the N-terminal end of the Lkb1 open reading frame.