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.＆lt;Br /＆gt;The cells are negative for expression of CSAp （CSAp-） and colon antigen 3, negative. There is a C -＆amp;gt; T mutation in codon 248 of the p53 gene resulting in an Arg -＆amp;gt; Trp substitution. The cells are positive for keratin by immunoperoxidase staining.
