Immunostaining of VM, ALDH1, Beclin1, and p16 in OSCC or the control tissue. A: Positive staining of VM structure in the OSCC tissue (100 magnification, black arrow is microvessel, red arrow is VM structure); B: Positive staining of VM in the OSCC tissue (400 magnification, black arrow is microvessel, red arrow is VM structure); C: Positive staining of ALDH1 in the cytoplasm of cancer cells (400 magnification); D: Negative staining of ALDH1 in the control tissues (100 magnification); E: Positive staining of Beclin1 in the cytoplasm of the cancer cells (400 magnification); F: Negative staining of Beclin1 in the control tissue (400 magnification); G: Negative staining of p16 in the cancer tissue (400 magnification); H: Positive staining of p16 in the cytoplasm and nucleus of the normal oral mucosa epithelial cells (400 magnification).