M6P/IGF2R loss of heterozygosity in human head and neck cancer. A single nucleotide polymorphism (c. 1197A>G transition) in exon 9 of the M6P/IGF2R was used to determine loss of heterozygosity in these representative samples [32, 33]. (A) Informative head and neck cancer without M6P/IGF2R loss of heterozygosity (i.e. both A and G polymorphisms expressed in tumor). (B) Informative head and neck cancer with M6P/IGF2R loss of heterozygosity (i.e. only G polymorphism expressed in tumor). (C) Non-informative head and neck cancer. Arrow, location of A>G polymorphism; arrowhead, A allele absent.