acetylgalactosaminyl-O-glycosyl-glycoprotein beta-1,6-N-acetylglucosaminyltransferase activity
UDP-N-acetyl-D-glucosamine:O-oligosaccharide-glycoprotein (N-acetyl-D-glucosamine to N-acetyl-D-galactosamine of N-acetyl-beta-D-glucosaminyl-1,3-N-acetyl-D-galactosaminyl-R) beta-1,6-N-acetyl-D-glucosaminyltransferase activity