PDCD1 and hepatocellular carcinoma: Analysis using mRNA data from the GEO database also suggested that the expression of PDCD1, CTLA4, CD244, BTLA, CD160, and LAG3 was upregulated when mRNA of TIM3/TIGIT or TIM3/2B4 was highly expressed, which is consistent with the results of a study on Hepatocellular carcinoma [44], where cells with elevated PD-1/TIGIT co-expression also had increased expression of TIM-3, LAG-3, and 2B4.