Although Serine/Threonine Kinase 3 (STK3), also known as Mammalian STE20-like protein kinase 2 (MST2), is a highly conserved kinase of the Hippo pathway, plays a critical role in immunomodulation, organ development, cellular differentiation, and cancer suppression, its phenotype and function in ESCC require further investigation. Here, STK3 is linked to cancer.