The Good
PhosSTOP is a dedicated phosphatase inhibitor, so it pairs flexibly with whichever protease inhibitor cocktail an experiment calls for. Each tablet is pre-measured for 10 mL of buffer, so there's no weighing or preparation of individual inhibitors. Its stated coverage includes the serine/threonine phosphatases PP1, PP2A, and PP2B, which is particularly relevant for β-catenin, since PP2A is a component of the destruction complex.
The Bottom Line
PhosSTOP is an effective and convenient phosphatase inhibitor for phosphorylation-sensitive work in mammalian cell lysates, and it is well suited to experiments where protease inhibitors are added separately. It is somewhat expensive, but for experiments where preserving phosphorylation is critical, it is a worthwhile choice.