However, Sp1 alone was not sufficient to promote CLDN4 expression, and ovarian cancer cells that expressed high level of CLDN4 exhibited high histone H3 acetylation and low DNA methylation at CLDN4 promoter region, indicating epigenetic regulations were involved in the development of chemoresistance in ovarian cancer cells [32]. The gene discussed is CLDN4; the disease is ovarian carcinoma.