The binding and cell uptake mechanisms of Pep42 were further investigated in cell surface GRP78 expressing cancer cells such as lung adenocarcinoma (A549), osteosarcoma (SJSA-1), and the human hepatoblastoma (HepG2) cell line along with the GRP78−, non-tumorigenic fibroblast cell lines as controls. Here, HSPA5 is linked to cancer.