Potential tumor suppressor genes, also found in other squamous cell carcinomas, have been discovered in the lost regions 2q33-q37.3 (PLCD4), 3p26.3-q11.1 (RBMS3, PLCD1, and CACNA2D3) and 11q12.2-q25 (CPT1A, CCND1, FGF4/FGF3, and PPP2R1B). This evidence concerns the gene PLCD4 and squamous cell carcinoma.