CD8A and neoplasm: Cholesterol and its derivatives critically modulate CD8+ T cell function in context-dependent manner: cholesterol enhances TCR signaling, yet tumor cells derived PCSK9 dysregulates CD8+ T cell cholesterol metabolism, thereby suppressing TCR signaling (123), while the oxysterol 27-hydroxycholesterol facilitates metastasis, an effect potently suppressed by CYP27A1 inhibition (124).