The principal regulatory mechanisms include heat shock proteins (HSPs), hypoxia‐inducing factor (HIF), EMT, interleukin‐6 (IL‐6)/hepatocyte growth factor (HGF)/cellular‐mesenchymal to epithelial transition factor (c‐MET)/signal transducer and activator of transcription 3 (STAT3) signal axis, cancer stem cells (CSCs), epigenetic modifications, and autophagy. Here, STAT3 is linked to cancer.