First, to claim the evidence for sterol superlattice formation, experiments should be performed using small sterol PR-619 fraction increments (e.g. ∼0.3 mol% which is comparable to the concentration errors, 0.1–0.4 mol% sterol relative to phospholipids, Liu et al., 1997) over a wide concentration range (e.g. 14–53 mol%). In this way, the dip/kink positions can be determined precisely, to the tenths of one mole fraction. In the range of 14–53 mol% sterol relative to diacylphospholipids, the theoretical critical sterol mole fractions for maximal superlattice formation are 14.3, 15.4, 20.0, 22.2, 25.0, 33.3, 40.0 and 50.0 mol% (Chong, 1994, Virtanen et al., 1995 and Liu et al., 1997). However, in some studies, one or two unexpected dips/peaks have been observed (e.g. ∼26.0–26.5 mol% in Liu et al., 1997 and Liu and Chong, 1999) and their physical origin is not clear. Second, in order to compare the spectral properties of all the samples on the same basis, the thermal history of all the samples in the same experimental set should be kept constant. Third, vesicles should be subjected to at least three heating/cooling cycles and a long incubation (>4 days) to attain the equilibrium lateral distribution. In summary, this type of experiment is laborious, but it is necessary in order to provide convincing evidence for superlattice formation.