Histologically the tumors formed from Oct4/GFP and Nestin/GFP cells are different. Hematoxilin and Eosin (H & E) staining was performed on tumors formed from GFP (+) cells isolated from Oct4/GFP and Nestin/GFP of A549 and H1299 cell lines (A-F). Tumors formed from 106 Vector/GFP cells were used as a control. (A,D) Oct4/GFP cells formed more differentiated tumors with acini surrounded by large amounts of stromal tissue. Black arrows mark stromal tissue. (B,E) The Nestin/GFP and (C,F) Vector/GFP tumors were poorly differentiated with minimal stromal tissue. (H) IHC show that the stromal tissue found in Oct4/GFP tumors stain for smooth muscle actin (SMA). (I) Very little SMA was expressed in the Nestn/GFP tumors.