NTSR1 and hemangioma: Although HNT-NTR showed sensitive NTR-responsiveness, hypoxia-activable ability and could detect hypoxic status in hemangioma cells, there were still some limitations of this chemosensor requiring further investigation: 1) When monitoring the treatment status of PRN in living HemECs, HNT-NTR could only reflect whether the cells were treated by PRN instead of reflecting the concentrations of PRN with a ratiometric method.