SEC inhibitor KL-1 is primarily used in cancer research, particularly in targeting transcriptional dependencies in tumor cells. It disrupts the super elongation complex (SEC), which plays a key role in the rapid expression of genes involved in cell growth and proliferation, such as oncogenes in leukemia. By inhibiting SEC, KL-1 effectively suppresses the expression of these critical genes, leading to reduced cancer cell viability and induction of apoptosis. It has shown promising activity in models of acute myeloid leukemia (AML) and other transcriptionally addicted cancers, making it a valuable tool compound for studying transcriptional regulation and developing targeted therapies.