SOX2 and cancer: Particular markers have been validated to differentiate CSCs in human cancers, including cell surface markers (CD9, CD24, CD133, CD44, EpCAM, etc.)and high enzymatic activities (aldehyde dehydrogenases—ALDH1) [23], as well as different oncogenes and transcription factors (transcription factors like Octamer binding transcription factor 4 (OCT), B Lymphoma Mo-MLV Insertion Region 1 Homolog (BMI1), North American Network Operations Group Homebox protein (NANOG), andsex-related high mobility group box (SOX)2, and SRY-Box 2 (SOX2)) [26].