Caution for the routine use of phenol red – It is more than just a pH indicator

Phenol red (PR) is the standard pH indicator in various cell and tissue culture media, as it provides a quick check for the health of the culture. PR has also been used in multiple protocols to detect cellular hydrogen peroxide as well as peroxidase activity from human peroxidase enzymes. The majority of promyelocytic leukemia cell lines (e.g. HL-60 cells) express myeloperoxidase (MPO), which may react with PR, especially as the latter is...