Consistently, confocal microscopy of freshly isolated MDA-MB231 tumor revealed Bi-FAP/mEnd-IL-based fluorescence exclusively in the tumor vasculature (Figure 7C, red arrow) and the tumor stromal fibroblasts, which could be recognized by their elongated morphology (Figure 7C, green arrow), but not the tumor cells (Figure 7C, yellow arrow). Here, FAP is linked to neoplasm.