In the biosynthesis of globo-series GSLs, the enzyme β1,3-galactosyltransferase5 (β3GalT5) expressed in cancer cells catalyzes the rate-limitingconversion of Gb4 to Gb5 (SSEA-3), which is subsequently transformedto Globo-H and SSEA-4 by fucosyltransferase 2 (FUT2) and sialyltransferase(ST3Gal1), respectively. The gene discussed is GNB5; the disease is cancer.