FOS and cervical carcinoma: In mammalian one/two-hybrid assays in cervical cancer HeLa cells transfected with a Gal4-dependent reporter, the basic region-leucine zipper (bZIP) DBDs of cJun-m1 and c-Jun-m1,5 fused to the Gal4 DBD were found to activate the reporter efficiently only in the presence of ATF2-VP16, but not with cFos (Figure 5b,c).