CIB1 (calcium and integrin-binding protein 1) is a small, ubiquitously expressed EF-hand calcium-binding protein that functions as a molecular adaptor regulating multiple cellular processes 1. Structurally, CIB1 contains a hydrophobic cleft that mediates interactions with numerous signaling partners including PAK1, ASK1, and PLK3 1. In calcium signaling, apo-CIB1 restrains premature integrin αIIbβ3 activation, while Ca2+-bound CIB1 recruits focal-adhesion kinase and amplifies cytoskeletal remodeling 2. CIB1 supports oncogenic PI3K/AKT and MEK/ERK pathways without possessing intrinsic enzymatic activity 1. In cancer, CIB1 promotes tumor progression through dual mechanisms: enhancing cell proliferation and survival via ERK1/2 and PI3K/AKT signaling, while also inhibiting apoptosis and mediating cell migration and angiogenesis 3. Clinically, CIB1 stabilization via USP14-mediated deubiquitination drives lenvatinib resistance in hepatocellular carcinoma through PAK1-ERK1/2 activation, identifying CIB1 as a therapeutic target 4. CIB1 is also upregulated under endoplasmic reticulum stress in pancreatic β-cells, suggesting relevance to diabetes pathogenesis 5. The CIB1-αIIbβ3 interface represents a selective antithrombotic checkpoint, with peptide and small-molecule inhibitors showing promise as antiplatelet agents 2.