KRAS and neoplasm: For instance, KRT8 intermediate cells, which transition between AT2 and AT1 cells, have been identified in normal lung tissues adjacent to LUAD lesions.253 The KRT8 cells expand in precancerous and cancerous stages and are implicated in tobacco-associated KRAS-mutant LUAD,253 marked as reduced differentiation, enhanced plasticity and harboring KRAS driver mutations.253 The high-plasticity cells can also play a role in later progression and development of tumor heterogeneity.