CD44 and cancer: To determine and identify the presence and distribution of stem-like cancer cells in pNETs, we initially stained tissue sections from human pNET patients with the CSC marker CD44, the pericyte/vascular smooth muscle cell marker α-SMA, and the lymphatic cell marker CD45 that can differentiate CD44+/CD45− CSCs from non-stem-like CD44+/CD45+ lymphatic cells.