The cyclic derivate 5,6,11,12,17,18,23,24-octahydrocyclododeca[1,2-b:4,5-b’:7,8-b’’:10,11-b’’’]tetraindole (CTet) is synthesized from 2,3’-DIM in the presence of formaldehyde under acidic conditions [52], inhibiting cell proliferation through overexpression of p21/CDKN1A in estrogen receptor-positive and triple-negative breast cancer cells [53]. Here, CDKN1A is linked to triple-negative breast carcinoma.