The (1) inducible form of Hsp70 (HSPA1A) (but not the constitutive form, Hsc70) and (2) the ER-localized glucose-regulated protein 78 (GRP78) (HSPA5) (Figure 1) have been found to be localized on the plasma membrane of a variety of tumor cell types including primary glioblastomas [20], squamous cell carcinoma of the head and neck (HNSCC) and non-small-cell lung carcinoma (NSCLC) [21,22], human oral dysplasia and squamous cell carcinoma [23], colorectal and gastric cancer [24], pancreatic carcinoma [25], osteosarcoma [26], and acute myelogenous leukemia [25,27]. Here, HSPA1A is linked to osteosarcoma.