PROM1 and thyroid gland papillary carcinoma: Flow cytometric analysis revealed that CD133 is expressed in two ATC cell lines, ARO (in which 7.02% of cells are CD133+) and FRO (in which 6.32% of cells are CD133+), but not in either of two well-differentiated papillary thyroid cancer cell lines (NPA and TPC) (Fig. 1A).