“…In particular, the visualization of degranulation has been aided by pHlourin, a pH sensitive variant of GFP that does not fluoresce at the acidic pH found in lytic granules, but upon exposure to neutral pH after degranulation fluoresces green (Miesenbock et al, 1998). By fusing pHluorin to the lumenal portion of granules using LAMP-1 or FasL, both of which sort to lytic granules (Peters et al, 1991; Bossi and Griffiths, 1999), individual degranulation events can be tracked by TIRF (Liu et al, 2011; Rak et al, 2011; Mace et al, 2012) or even by confocal of NK cells in conjugates (Mace et al, 2012). …”