Fig. 2
From: Pathological transition as the arising mechanism for drug resistance in lung cancer
Pathological transition of different lung cancer subtypes. Lung cancer can be divided into two subtypes: NSCLC and SCLC. NSCLC can be further divided into three subtypes: ADC, SCC, and LCC. ADCs are considered to originate from alveolar type II cells, club cells or BASCs. SCC frequently found at more proximal airways is presumably derived from basal cells. SCLC is typically derived from neuroendocrine cells. Pathological transition is observed in clinic including lung ADC-to-SCC transdifferentiation and ADC or SCC-to-SCLC transition. Loss of LKB1 or RB1 potentially contributes to the squamous and SCLC transition, respectively. NSCLC non-small cell lung cancer, SCLC small cell lung cancer, ADC adenocarcinoma, SCC squamous cell carcinoma, LCC large cell carcinoma, BASC bronchio-alveolar stem cell, LKB1 liver kinase B1, RB1 retinoblastoma