The glucose regulated protein 78 (GRP78) is traditionally
regarded as a resident protein of the endoplasmic reticulum
(ER) and functions as a molecular chaperone [4]. In addition
to its chaperoning function,many data suggest that GRP78 is
amultifunctional protein and plays critical roles in the resistance
to chemotherapy agents, proliferation, invasion, and
metastasis of many human cancers [5–9].
GRP78 is expressed in the endoplasmic reticulumin normal
conditions but also is expressed at an elevated level on the
surface ofmany tumors and disseminated tumor cells [10, 11].
The cell surface GRP78 functions as a signaling receptor and
plays important roles in the regulation of the proproliferative/
antiapoptotic and promigratory signaling pathways [12, 13].