FIG. 1.
High-efficiency ablation of the LKB1 protein selectively in skeletal muscle. (A) LKB1 expression was not significantly altered for wild-type (WT) mice compared to that for mice harboring one (lox/+) or two (lox/lox) alleles in gastrocnemius muscle lysates. Heterozygotes (+/−) showed approximately 50% of control LKB1 expression, while MLKB1KO (−/−) mice showed nearly complete loss of LKB1 expression. (B) LKB1 activity was assessed in an in vitro kinase activity assay using LKB1tide as the substrate. Consistent with protein data, +/− and −/− animals showed reduced LKB1 activity compared to controls. (C and D) Muscles from MLKB1KO animals (−/−) show nearly complete depletion of the LKB1 protein (C), while expression is not affected in nonmuscle tissue (D). Gastroc, gastrocnemius; TA, tibialis anterior; Sol, soleus. Data are means ± SEM; n = 3 to 6/group. *, P < 0.05; ***, P < 0.001 versus control results (+/+).