The TAGLN protein, also known as transgelin, is a member of the calponin family of actin-binding proteins. It is highly expressed in vascular and visceral smooth muscle cells and serves as an early marker of smooth muscle differentiation. TAGLN is involved in calcium-independent smooth muscle contraction and acts as a tumor suppressor. Its expression is often lost during cell transformation and tumor development, coinciding with cellular plasticity. In addition to its role in smooth muscle, TAGLN has been implicated in various cellular processes, including epithelial cell differentiation and immune responses. The protein consists of an N-terminal calponin homology (CH) domain and a C-terminal calponin-like (CLIK) domain. Studies have shown that TAGLN can inhibit the proliferation and invasion of cancer cells, such as colorectal carcinoma cells, and promote apoptosis. Furthermore, TAGLN expression is upregulated in certain types of tumors, such as NF1-associated malignant peripheral nerve sheath tumors, due to hypomethylation in its promoter region. Overall, TAGLN plays a multifaceted role in cellular function and disease, particularly in the context of smooth muscle and cancer biology.