Dioxin, produced as a by-product of various industrial chemical processes, is suspected of contributing to the development of cancer and birth defects in animals and humans. It apparently acts by entering cells by simple diffusion and binding to proteins in the cytoplasm, then altering the pattern of gene expression. Which of the following are likely to be the cytoplasmic proteins to which dioxin binds?
A) Nucleosomesb.
B) DNA polymerasesc.
C) Enhancersd.
D) Transcription factorse.
E) Growth factor receptor.

Transcription factors are the DNA-binding proteins that serve to regulate transcription in eukaryotes. Transcription factors may be activators that upregulate the gene expression or may serve as repressors that negatively affect the gene expression. According to the given information, dioxin binds to the cytoplasmic proteins and this binding affects the pattern of gene expression in the cells. This means that dioxin is binding to the transcription factors to alter the gene expression in the cells.

For instance, it may bind to the transcription factor that otherwise regulates the expression of the gene encoding the protein involved in the regulation of cell division and thereby resulting in cancer.