FHL2 (four and a half LIM domains 2) is a multifunctional LIM domain protein that serves as a molecular adapter linking signaling pathways to transcriptional regulation. FHL2 negatively regulates the transcriptional repressor E4F1 and inhibits FOXO1-mediated apoptosis by enhancing FOXO1-SIRT1 interaction [UniProt]. It also negatively regulates calcineurin/NFAT signaling in cardiomyocytes. In adipogenesis, FHL2 acts as a positive regulator of adipocyte differentiation and proliferation while suppressing apoptosis through p53 and BAX downregulation 1. FHL2 exhibits context-dependent roles in cancer. In gastrointestinal cancers, FHL2 is upregulated and promotes tumorigenesis; FHL2 suppression induces cell differentiation and inhibits tumor formation in xenograft models 2. Conversely, in lung adenocarcinoma, FHL2 expression by cancer-associated fibroblasts enhances metastasis and angiogenesis through osteopontin secretion 3. FHL2 is identified as a biomarker in idiopathic pulmonary fibrosis, correlating with immune cell infiltration 4. In pulmonary arterial hypertension, FHL2 is part of a PPARγ-p53-mediated vasculoprotective program promoting endothelial survival and angiogenesis 5. This dual role—acting as both tumor suppressor and oncoprotein depending on tissue context and signaling environment—classifies FHL2 as a "double-edged sword" in disease pathogenesis 6.