tokens: In contrast , 3 , 3 ' , 4 , 4 ' , 5-PeCB , a congener of coplanar structure , as well as 2 , 3 , 7 , 8-TCDD did not induce apoptosis in these human monocytic cells , although they potently induced CYP 1A1 in human hepatoma Hep G2 cells .