PLK1 and non-small cell lung carcinoma: Although approximately 20% of NSCLC tumors are mesenchymal (Akbani et al, 2014; Chen et al, 2014) and predicted to be sensitive to Plk1 inhibition, the reversibility of EMT and intratumoral heterogeneity may diminish the efficacy of Plk1 inhibitors, contributing to low response rates.