Abstract: Compositions of matter consisting of a family of related nucleotide sequences that encode proteins, termed BRCA1 Modulator Proteins, that bind to the tumor suppressor gene product BRCA1, and methods of using the nucleotide sequences and the proteins encoded thereby, to diagnose and/or treat disease where the BRCA1 Modulator Proteins have an apparent molecular weight of 45-97 kdaltons and are characterized by having at least one leucine zipper domain, and optionally a zinc finger domain.

Abstract: Peptides, that inhibit GAP stimulated ras p21 hydrolysis of GTP; peptides that mediate dissociation of GDP from ras p21-GTP complex; and antibodies to the peptides are described. These peptides are useful as cancer diagnostics and therapeutics, particularly to detect cancer cells with an over expression of normal or oncogenic ras p21 protein and to treat cancer caused by ras oncogene. Methods for assaying products of oncogenes using the described peptides and antibodies are also disclosed. Method for treating cancer caused by ras oncogenes is also disclosed.