WNK2 and cancer: Studies have revealed that emodin suppresses cell growth and proliferation through the attenuation of oncogenic growth signaling, such as protein kinase B (AKT), mitogen-activated protein kinase (MAPK), HER-2 tyrosine kinase, Wnt/-catenin, and phosphatidylinositol 3-kinase (PI3K) that leads to apoptosis in several cancer cell types [12,13,14,15,16,17], and regulates cancer cell invasion and metastasis [18,19,20,21,22,23,24].