Using flow cytometric analysis, we observed that in all of the tested HCC cell lines (MHCC97H, MHCC97L, HepG2 and SMMC-7721), CD90 was consistently expressed in a small population (0.9 % to 3.1 %, Additional file 2: Figure S1A), even under cell sphere formation conditions, which increased in all four cell lines up to 11.8 % (Additional file 2: Figure S1B). The gene discussed is THY1; the disease is hepatocellular carcinoma.