Protein phosphatase-1 inhibition induces high SCEs in normal whole blood cultures.

Effect of 1,25,50 and 75 nM of okadaic acid (OA) on human lymphocytes from healthy individuals in culture has been investigated. To our surprise, we observed induction of significantly high sister chromatid exchanges (SCEs) at concentrations known to inhibit both protein phosphatase-1 (PP-1) and protein phosphatase -2A (PP-2A). However, 1 nM okadaic acid, known to inhibit PP-2A alone, did not induce this cellular feature/phenotype. This novel preliminary observation lays foundation for investigating further the role of PP-1 inhibition in governing as yet unknown finer controls in the induction of high SCEs, the mechanism for which has eluded answers till date.