However, LOH around hMLH1 locus was detected in four of 17 cell lines (24%) and 16 of 54 primary tumours (30%) with normal hMLH1. This result suggests that another unidentified tumour suppressor gene or genes close to hMLH1 gene may exist and play a role in colorectal carcinogenesis, especially in non-mucinous cancer with MSS phenotype. This evidence concerns the gene MLH1 and neoplasm.