CD274 and carcinoma: - Carcinoma glycocalyx and tumor-surface sialic acid expression: Direct immune-cell repression via Siglec receptors on CD8+ T cells (and NK cells)- Carcinoma cell co-inhibitor ligands (e.g., PDL1- binding to PD1; Galectin-9 binding to TIM3)- Tumor sialic acid masking of ligands for NKG2D activating receptor on CD8+ T cells (and NK cells)