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. DNA polymerasesc. enhancersd. transcription factorse. growth factor receptors

Transcription factors are the proteins present in the cytoplasm. The function of the transcription factors is to regulate the gene expression by binding to the regulatory sequence. The binding site for a transcription factor is mostly present upstream of initiation codon or maybe within the gene itself.

The transcription factor bound to the regulatory site interact with RNA polymerase to regulate the expression of the gene. According to the given information, dioxin binds to the cytoplasmic proteins and alter the gene expression. These cytoplasmic proteins must be transcription factors for the target gene of dioxin.