Supplementary Figure 7: Comparison of RS-PACT of BphP1-expressing U87 tumor and unlabeled U87 tumor.

In vivo ON state (the first column), OFF state (the second column) differential (the third column), and overlay (the fourth column) PA images of a BphP1-expressing U87 tumor (a) and an unlabeled U87 tumor serving as a control (b). The two types of tumor cells were subcutaneously injected into two different sites on the flank of the same mouse. The differential image of the BphP1-expressing U87 tumor has a substantially superior image contrast to that of the unlabeled tumor. The overlay images show the BphP1 signal in color and the background blood signal in gray. A global threshold was applied to all the differential images with a threshold level at three times the noise level.