Mucin 1 (MUC1), a transmembrane mucin that serves a protective role by inhibiting extracellular pathogens from entering epithelial cells is also implicated in forming cancerous cells through dimer formation. Upon expression and localization in the membrane, MUC1 proteins form cysteine-dependent homodimers through the juxtamembrane domain CQC motif. The dimers are then trafficked to the nucleus, upregulating genes involved in cell mitosis and in the formation of several forms of cancer, including cancer of the breast, pancreatic and ovarian. Therefore, a better understanding of the interactions that lead to dimerization can help in the development of targeted therapeutics that inhibit dimer formation and improve quality of life in patients that have mucinous carcinomas. Mucin 16 (MUC16) is another transmembrane mucin that has also been associated with cancers of the ovary. However, little research has been conducted to better understand MUC16’s interactions and their contribution to cancer formation. We hypothesize that cysteine residues at the end of the transmembrane domain in MUC16 (FWAVILIGLAGLLGVITCLIC) form inter-disulfide bridges, similarly to that of the juxtamembrane CQC in MUC1 dimers. To better understand the interactions between amino acid residues in the transmembrane domain of MUC16, we utilized the ToxR assay, a colorimetric assay that reports dimerization via enzymatic activity. Our results show that the cysteines in MUC16 contribute to dimer formation. However, the contribution is not as significant as in the case of MUC1. This leads us to believe that there are other non-covalent interactions that play a role in the formation of MUC16 dimers.