RAC1 and neoplasm: The SPON2-a4b1 integrin signaling pathway upregulates F-actin recombination, activates Rac1 and RhoA, and encourages the attraction of m1-like macrophages.[39] Research has revealed that the thyroid hormone-regulated protein SPON2 inhibits the migration and invasion of HCC cells.[20] These findings demonstrate that SPON2 is a key factor in mediating the immune response in HCC against tumor cell growth and migration.[21]