GABBR1 and nasopharyngeal carcinoma: Interestingly, when the GABBR1 transcript and protein levels in NPC cell lines were examined, down-regulation of GABBR1 protein in two NPC cell lines, BM1 and HK1 (AA genotype at rs29232), was observed compared with the immortalized nasopharyngeal epithelial cell line NP69 (AG genotype at rs29232).