SOX9 and cancer: We observed a positive and statistically significant correlation between the levels of PHGDH with the expression of the major pluripotency transcription factor Oct4 (R = 0.2782) as well as other markers of cancer stemness, including MYC (R = 0.2693), SOX9 (R = 0.3794), and CD133 (R = 0.4909)12,29–31 (Fig. 2a).