Poly A+ RNA isolated from the human breast cancer cell line MCF-7 was fractionated by
sucrose gradient centrifugation and those fractions enriched in oestrogen receptor (ER)
mRNA were used to prepare randomly primed cDNA libraries in the λgt10 and λgt11 vectors.
Clones corresponding to the ER were isolated from both libraries after screening with either
ER monoclonal antibodies (λgt11) or synthetic oligonucleotide probes designed from two
peptide sequences of purified ER (λgt10). Five cDNA clones were isolated by antibody …