label: alpha-L-Fuc-(1->2)-beta-D-Gal-(1->3)-D-GlcNAc + GDP-beta-L-fucose = alpha-L-Fuc-(1->2)-beta-D-Gal-(1->3)-[alpha-L-Fuc-(1->4)]-D-GlcNAc + GDP + H(+)
label_lc: alpha-l-fuc-(1->2)-beta-d-gal-(1->3)-d-glcnac + gdp-beta-l-fucose = alpha-l-fuc-(1->2)-beta-d-gal-(1->3)-[alpha-l-fuc-(1->4)]-d-glcnac + gdp + h(+)