STK11 and cancer: Immunohistochemical screening on FFPE tissue of both total LKB1 protein and AMPKthr172 as clinical biomarkers may provide an effective alternative approach to costly whole-gene or DNA-based sequencing, as it has the potential to capture most mechanisms conferring protein instability, loss-of-function mutations, and deletions, suggesting that protein degradation can be used as a means to identify the loss of LKB1 in cancer.