For example, through the sphere formation model, CD44+ cells in NSCLC were found to initiate tumorigenesis by aberrant expression of octamer binding transcription factor 4 (OCT4), SRY-box transcription factor 2 (SOX2), and Nanog homeobox (NANOG), genes known to be regulators of self-renewing and differentiation abilities in cells [24]. Here, CD44 is linked to non-small cell lung carcinoma.