MGAT4A and endometrial cancer: This process leads to the formation of tri‐ and tetra‐antennary N‐glycans on both membrane‐bound and secreted proteins within the Golgi apparatus, thereby contributing to LacNAc modification (Figure S2H, Supporting Information).[30] As the initiated enzymes catalyzing β1,4‐GlcNAc branches in N‐glycan, MGAT4A was predominantly expressed in tumor cells, while MGAT4B was found in tumor‐infiltrated stromal cells as per the Human Protein Atlas endometrial cancer database (Figure S2I, Supporting Information).