On August 28, 2017, Paula L. Rosson, Senior Vice President and Chief Accounting Officer of MPLX GP LLC and principal accounting officer of MPLX LP (the Partnership) informed the Partnership that she has elected to remain in the Partnership's Denver, Colorado division office and accept a senior management role with MarkWest Energy Partners, L.P., a wholly-owned subsidiary of the Partnership. Ms. Rosson's election to remain in Denver is in lieu of relocating to the Partnership's headquarters in Findlay, Ohio to continue service as the Partnership's principal accounting officer long term. In the interim, Ms. Rosson will continue to serve as the principal accounting officer of the Partnership until a successor is appointed.