INA-UV treatment blocks SDF1α induced CXCR4 signaling. The fluorescence emission of Fura 2 was recorded at 510 nm using simultaneous excitation at 340 and 380 nm. The ratio of the 2 emission signals obtained, 340/380, is plotted over time. SDF1α was added at time 50 sec as indicated and further on the ionophore 4-bromo A-23187 was added at time ~160 sec as indicated. The same experiment was carried on SupT1 cells (dark curve) or SupT1 cells treated with 15 μM INA-UV (grey curve).