The expression of the ACTRIIB protein was also detected in NPC cell lines, including HNE1, HNE2, HONE1 (poorly differentiated squamous carcinoma), CNE1 (well-differentiated squamous carcinoma), 5-8F (poorly differentiated with high metastasis), and 6-10B (low metastasis), and immortalized nasopharyngeal epithelial cells NP69. The gene discussed is ACVR2B; the disease is squamous cell carcinoma.