TPPS can be used as a non-cytotoxic probe for detecting tumor location.In Vitro: TPPS (0-20 μg/mL) shows no toxicity in Vero and HEp-2 cells in vitro and predominantly locates in the soluble and protein fractions in cells.In Vivo: TPPS4 shows the highest tumor to tissue ratios after 96 hours injection with a dose dependent manner[2].TPPS4 appears to be cleared through the kidneys and absolute concentrations there are reduced with increasing time after injection[2].