STK11 and Peutz-Jeghers syndrome: Biallelic loss of lkb1 is embryonic lethal in mice, yet, heterozygous lkb+/− mice develop gastrointestinal hamartomas that closely recapitulate the pathophysiology of the PJS patients (Ylikorkala et al, 2001; Bardeesy et al, 2002; Jishage et al, 2002; Miyoshi et al, 2002; Rossi et al, 2002; Katajisto et al, 2008).