Heat shock and chaperone/cochaperone proteins are highly expressed by brain tumor xenografts or syngeneic tumors grown in vivo compared with normal brain. Western blots of tumor or brain lysates were probed with the antibodies listed on the left; actin probe is shown as a loading control, as is the Ponceau Red-stained blot shown on the right. The panel for HSP27 is broken into three parts to indicate that the murine tissues (SMA560 and brain) were probed with different HSP27 antibodies than were the human xenograft tumors (D54MG and D341MED).