This update of the I blood group system (Cooling L. Polylactosamines, there’s more than meets the “Ii”: a review of the I system. Immunohematology 2010;26:133–55) continues to show the Ii antigens to be increasingly recognized as important posttranslational modifiers regulating cell adhesion, signaling, differentiation, and cancer. Ii antigens can modulate the immune response through the galectin lattice, as well as influence specific protein–protein interactions. Changes in