PROM1 and cancer: As a result, EMX2 expressions did not show any correlation with those of TERT (encoding telomerase reverse transcriptase) (Figure 4A,D), PCNA (encoding proliferating cell nuclear antigen) (Figure 4B,E), or PROM1 (encoding CD133, a well-known cancer stem cell marker) (Figure 4C,F) in either 20 ESCC cell lines or 18 ESCC tissue samples.