GSK3B and neoplasm: Unlike these differences, cell surface PD-1 expression was measured on tumor-infiltrating lymphocytes (TILs) and showed a clear reduction in the double and Gsk3b cKO mouse cells (Figure 2E) and a lesser reduction in TILs from the Gsk3a cKO mice, consistent with the Pdcd1 gene expression data from the spleen (Figure 2C).