STAT3 and lung cancer: IL‐6 plays a crucial role in promoting lung cancer progression, metastasis, and drug resistance by upregulating the T‐cell immunoglobulin domain and mucin domain 4 (TIM‐4) via the NF‐κB pathway or by activating signal transducer and activator of transcription 3 (STAT3) and insulin‐like growth factor‐1 receptor (IGF‐1R) to induce epithelial‐to‐mesenchymal transition (EMT).