CD4 and hepatocellular carcinoma: HCC progression: In a study involving 39 matched tissue samples from HCC, non-tumor, and leading-edge specimens of 13 HCC patients, using single-cell-scaled time-of-flight mass cytometry (CyTOF), it was shown that the number of CD4 effector memory T cells (Tems) and Tregs gradually increased from the non-tumor region to the HCC tumor region [102].