Antibody response to N-glycan deletion GPC showed higher titer to mutant GPC than to WT GPC. After three rounds of immunization, sera were collected, and the titers were determined using cell-based ELISA. A–L The titer of the indicated serum to the mutated GPC. M The titer of the indicated serum to WT GPC. *P < 0.05, **P < 0.01, ***P < 0.001, compared to WT.