The invention provides a molecule that inhibits or prevents an interaction between a Src family kinase and an androgen or estradiol receptor for use in preventing or treating a non cancerous condition in which an activity of AR and/or ER is a contributory factor in a subject or for use in preventing or treating a cancerous condition in which an activity of AR and/or ER is a contributory factor in a subject who wishes to preserve fertility or for use in preventing or treating a gynaecological condition in which an activity of AR and/or ER is a contributory factor in a subject. Preferably the molecule comprises or consists of the structure: B[(Pro) X His Pro His Ala Arg lle Lys] R or B[lys ile arg ala his pro his x (pro)] R or a derivative or fragment thereof wherein B is a first chemical moiety j is 0 or 1 n is an integer from 1 10 X is any amino acid r is an integer from 0 to 2 m is an integer from 1 to 3 R is a second chemical moiety p is 0 or 1 and [lys ile arg ala his pro his x (pro)] is the retro inverso peptide of [(Pro) X His Pro His Ala Arg Ile Lys].
