Initial characterisation of oestrogen receptors in canine mammary tumour lines maintained in nude mice.

Proteins binding oestradiol with high affinity and low capacity have been characterised and quantitated in 4 newly established canine mammary tumour lines, MS306, V5500, F5010 and PD6014, maintained in nude mice. These receptor proteins, specific for oestrogens, were found in all the tumour lines, both in initial implants and all subsequent passages. Receptors had equilibrium dissociation constants for oestradiol in the range of 33-210 pM, and sedimentation coefficients of 4 S and 8 S.