Cytochalasin J is primarily used in biological research to study cellular processes, particularly those involving the cytoskeleton. It is known to inhibit actin polymerization, which makes it a valuable tool for investigating cell motility, shape, and division. Researchers utilize it to disrupt actin filaments, allowing them to observe the effects on cellular functions and signaling pathways. Additionally, it has been employed in studies related to cancer, as it can help elucidate the role of actin in tumor cell invasion and metastasis. Its ability to interfere with actin dynamics also makes it useful in developmental biology to understand tissue organization and morphogenesis.