CD51, also known as integrin alpha-V, is reported to be expressed in nestin+ colorectal cancer stem cells.30 CD51 was also used to isolate nestin+ mesenchymal stem cell (MSCs) in human fetal bone marrow.31 However, CD51 cannot be used to identify adult nestin+ MSCs, as both osteoblasts32 and megakaryocytes33 express CD51 in human adult marrow. Here, ITGAV is linked to colorectal cancer.