A method of treating cancer in a subject is provided. The method includes administering a splice modulating oligonucleotide to the subject in an amount effective to provide a therapeutic benefit to the subject. In the method, the oligonucleotide modifies splicing of a pre-mRNA encoding a polypeptide, and either: reduces expression of the polypeptide if the polypeptide promotes cancer cell survival, proliferation, and/or metastasis, or promotes angiogenesis, or a combination thereof; or increases expression of the polypeptide if the polypeptide inhibits cancer cell survival, proliferation and/or metastasis, or inhibits angiogenesis, or a combination thereof. Similar methods of treating diseases involving prolactin or the prolactin receptor are also provided.