Ectopic CT45A1 expression in two MSI‐H CRC cell lines did not alter the surface expression of MHC‐I (Fig. S2A,B), PD‐L1 (Fig. S2C,D), or sialylated ligands for Siglec‐7 (Fig. S2E,F) or Siglec‐9 (Fig. S2G,H). The gene discussed is SIGLEC9; the disease is colorectal carcinoma.