Immunostaining of frozen sections of tongue tissues after 23 weeks showed that with progression of OSCC, the expression of MCT4 persisted and was primarily detected in foci within the upper layers of the epithelium (Figures 4E,F) and often in CIS lesions having a papillary morphology (papillary carcinoma in-situ). Here, SLC16A3 is linked to in situ carcinoma.