XPO1 and glioma: Although Shintani et al., (2016) studied the XPO1 expression in CRC tissue samples, they did not find such association in CRC tissues which may attribute to the large differences in the sample sizes in each of well and poorly differentiated tumor groups; others were found such association in other types of cancers such as ovarian cancer (Noske et al., 2008), glioma (Shen et al., 2009) and the XPO1 expression was increased from well to poorly differentiated breast tumors (Yue et al., 2018).