61 A comprehensive review led by Tianlin He and his graduate student Keke Lv shed new light on the intricate dynamics of solid tumours and their relationship with the tumour microenvironment. The authors explore the multifaceted roles of cancer-associated fibroblasts as pivotal mediators within the tumour microenvironment, offering groundbreaking insights into their origins, classifications, and functions in cancers such as pancreatic, rectal, lung, and breast cancer. This review not only enhances understanding of tumour biology but also opens new avenues for targeted cancer therapies. The findings were published in the journal Molecular Biomedicine. The authors emphasise that the development of solid tumours stems from complex communication and crosstalk among the tumour microenvironment’s components. This imbalance between parenchymal cells and the surrounding microenvironment drives tumour progression. The study highlights the remarkable plasticity and heterogeneity of cancer-associated fibroblasts, positioning them as key players in these processes. The review meticulously examines how cancer-associated fibroblasts interact with other components of the tumour microenvironment. Cancer-associated fibroblasts influence both innate and adaptive immune cells. Through direct contact, paracrine signalling, and other mechanisms, they polarise innate immune cells like macrophages, neutrophils, and mast cells towards pro-tumour subtypes. This effect is further reinforced through a feedback loop with immune cells, ultimately facilitating tumour immune escape. Cancer-associated fibroblasts secrete cytokines such as TGF-β and proteases like MMPs and LOX, disrupting the delicate balance between extracellular matrix fibre formation and degradation. This leads to extracellular matrix fibrosis, which in turn activates the YAP pathway in cancer-associated fibroblasts through integrins, exacerbating tumour progression. Cancer-associated fibroblasts also engage in metabolic regulation under stress conditions such as inflammation and hypoxia. By compartmentalising tumours into aerobic and hypoxic regions, cancer-associated fibroblasts and tumour cells enhance energy turnover and nutritional metabolism through the exchange of cytokines and metabolites. The review underscores the paradoxical roles of cancer-associated fibroblasts in cancer. While they promote tumour growth and immune evasion, targeting cancer-associated fibroblasts offers significant therapeutic potential. Existing drugs and clinical trials targeting cancer-associated fibroblasts are discussed in detail, providing a roadmap for future research. The authors conclude that the tumour microenvironment should be viewed as a dynamically balanced network where various cellular components work as an integrated system. By focusing on cancer-associated fibroblasts as central pivots, the study reveals novel perspectives for clinical cancer treatment. These include strategies to restore the equilibrium of the tumour microenvironment, ultimately curbing tumour growth and enhancing patient outcomes.