The development of agents to molecular targets associated with specific breast cancer subtypes has the potential to improve patient treatment, as evidenced by the ERBB2 monoclonal antibody trastuzumab (Herceptin).Although calcium transporters are widely used and researched in the treatment of hypertension and pain, it has only been recently recognised that specific isoforms of calcium channels and pumps may be molecular targets in the treatment of specific cancers.Our research group has characterised the expression of particular calcium channels and pumps in breast cancer including transient potential receptor channels (TRPs) and plasma membrane calcium ATPases (PMCAs).These studies indicate that the profile of calcium transporter transcription is a characterising feature of specific breast cancer molecular subtypes e.g.luminal versus basal subtypes.The mechanism of transcriptional up-regulation has not been widely studied, although our recent work highlights a potential involvement of gene duplication for some calcium transporters.Inhibition of specific calcium pump and channel isoforms using siRNA inhibits the proliferation of breast cancer cell lines in which they are over expressed e.g.MCF-7, T-47D and MDA-MB-231.Collectively, our studies indicate that specific calcium transporter isoforms may represent new molecular targets for breast cancer due to the role of calcium in cancer relevant pathways including proliferation, invasion, and apoptosis.An advantage of these targets is the demonstrated ability of this class of proteins for pharmacological modulation and the potential for chemogenomic dug discovery approaches.