PECAM1 and neoplasm: We used 30-μm fixed sections of tumour for two-photon imaging to simultaneously capture the fluorescence lifetime of eGFP in tumour cells expressing the Picchu-X biosensor and to measure the distance of the biosensor-expressing tumour cells to the closest blood vessel and tumour-associated macrophage (TAM), which were stained with anti-CD31 and F4-80 antibodies, respectively.