CD44 and neoplasm: To further examine the tumor response to CD44-IR700-mediated PIT, histological analysis was performed on MDA-MB-231 tumors resected from CD44-IR700-treated mice and other control agent-treated mice at 4 day p.i. In the CD44-IR700-treated unirradiated tumors, the H&E stained images of tumor sections clearly demonstrated viable cells with some central necrosis as shown in the representative images in Fig. 6a.