It was originally slated for launch using an Atlas V 531, but was transferred to Proton due to a large backlog of Atlas launches.
List of Proton launches (2010-2019)
The last two planned Shuttle flights are due to add one of the two final elements of ISS, followed by one last Proton launch with the planned delivery of the ERA.
List of Proton launches (2000-2009)
Another Briz-M broke up on 16 October 2012 after failing on the Proton launch of 6 August.
Prices range from about $4,300/kg for a Proton launch to about US$40,000/kg for a Pegasus launch (2004).