CD44 and gastric cancer: This study analyzed the expression changes in Octamer-binding transcription factor 4 (OCT4), Nanog homeobox (NANOG), SRY-Box Transcription Factor 2 (SOX2), Cluster of Differentiation 24 (CD24), Cluster of Differentiation 44 (CD44), Cluster of Differentiation 90 (CD90), and Mucin short variant S1 (MUC1) genes, as candidate markers for gastric cancer stem cells, chemoresistance, spheroid formation, and invasiveness (Nishii et al., 2009; Takaishi et al., 2009; Zhang et al., 2011; Jiang et al., 2012; Saeki et al., 2014; Terzioğlu et al., 2018).