GSK-J5 is an isomer of GSK-J4 and a prodrug for negative control GSK-J2. GSK-J2 is a negative control for GSK-J1, which is an inhibitor of the H3K27 histone demethylases JMJD3 and UTX. GSK-J5 did not have any effect on TNF-α protein production that depends on both JMJD3 and UTX. GSK-J5 is a weak inhibitor of JMJD3.