Sambucus Nigra (Elderberry Bark) Lectin (SNA, EBL), fluorescein (FITC), is a bright-green SNA-fluorophor conjugate. SNA belongs to the group of type 2 ribosome-inactivating proteins and is composed of an A-chain with enzymatic activity and a B-chain with carbohydrate-binding activity. SNA can induce apoptosis through the caspase-dependent pathway at low concentrations. This effect depends on the carbohydrate binding of the B-chain and is independent from the catalytic activity of the A-chain. In colon cancers, it has been reported that 90% of carcinomas express increased levels of sialic acid, linked to galactose residues on the surface of tumor cells, that is detectable with SNA.
