ROR1 and ovarian cancer: The expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) is closely related to the phenotype of ovarian cancer stem cells, peritoneal metastasis, and the development of resistance to chemotherapy (Zhang et al., 2012; Zhang H. et al., 2014; Zhang S. et al., 2014; Henry et al., 2017; Karvonen et al., 2019).