HAS2 and neoplasm: In fact, apart from the differences in the kinetics and regulation, HAS2 and HAS3 also differ in the size of HA synthesized: HAS2 produces polysaccharides larger than 2 MDa; whereas, HAS3 synthesizes molecules ranging from 0.2 to 2.0 MDa [31], and it might as well be responsible for a different localization of the GAG in the tumor mass.