As in LSCs, an important role for PTEN inactivation/deletion in conferring CSC properties has been reported in several types of solid tumors, which include glioblastoma [94], hepatocellular carcinoma (HCC) [95], prostate carcinoma [96,97], lung adenocarcinoma [98], and breast carcinoma [99]. The gene discussed is PTEN; the disease is hepatocellular carcinoma.