Alkaline phosphatase activity in cultured skin fibroblasts from fibrodysplasia ossificans progressiva

Alkaline phosphatase activity in four strains of cultured skin fibroblasts obtained from a patient with fibrodysplasia ossificans progressiva was at the low normal range. The enzyme activity in normal fibroblasts significantly increased at late confluency. It appears that the high levels of alkaline phosphatase activity reported in biopsies of lesions are not genetically determined but are secondary events of local tissue reaction.