KRT7 and neoplasm: All the Akt1/N-Ras-induced tumor cell lines and Hepa1-6 expressed nearly no CK7/Krt7 (keratin 7) (Figure 1D; Supplementary Figure S1C), and the Akt1/N-Ras-induced tumor cell lines but not Hepa1-6 expressed significant amount of the biliary/progenitor cell marker, CK19/Krt19 (keratin 19) (Figure 1D; Supplementary Figure S1D), which suggests that these Akt1/N-Ras-induced tumor cell lines possess the properties of hepatic progenitor cells but are not derived from cholangiocytes.