Fig. 3. C1462A(L327M) mutant Stat5b is unable to generate ĚNO. Confocal imaging of nitric oxide accumulation in wild and mutant Stat5b-DsRed plasmid transfected MIN6 cells using DAF-FM DA. Increased nitric oxide levels were found on overexpression of STAT5B (wStat5b-DsRed) while no significant change was observed in mutant STAT5B (mStat5b-DsRed) with weaker DNA binding ability, compared to empty vector transfected and untransfected cells. The cells were treated with 10ÁM DAF-FM DA for 30 minutes followed by treatment with PRL, incubated for further 30 minutes, and imaged at 358 nm, 488 nm and 568 nm excitation. Nuclei were stained with DAPI.