Human Caucasian rectum adenocarcinoma. Established from a Grade IV adenocarcinoma of the rectum of a 53 year old Caucasian male. The cells produce CEA and electron microscopy reveals brush borders.Br /;The cells are negative for expression of CSAp (CSAp-) and colon antigen 3, negative. There is a C -> T mutation in codon 248 of the p53 gene resulting in an Arg -> Trp substitution. The cells are positive for keratin by immunoperoxidase staining.