Fig. 2.

Membrane proteomic analysis of the sphere-forming cells and the adherent cells in HNSCC cell cultures. A, membrane proteins extracted from adherent cultured cells and spheres (the gel was stained with silver nitrate). B, Venn diagrams of the identified HNSCC membrane proteins and those found in two datasets of hESC membrane protein signatures published by Prokhorova et al. (10) and Gu et al. (11). C, functional networks of the proteins common to the datasets were analyzed using GeneGo MetaCore software. Two networks were identified: EGFR/CD44/HSP70/HSP90 and integrin alpha-6/beta-4/SLC3A2. D, the expression of seven membrane proteins identified via MS was evaluated with Western blotting, and five of them were consistently up-regulated in the sphere cells. E, densitometric analysis of the Western blot staining levels.