Expression problems in mammalian cells PLEASE HELP!!!

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Hi I am trying to express a 3X-flag tagged protein that's ~82kDa (with tag) in 293T cells. After transfecting the vector, I performed a Western blot to check for expression. On the Western blot my protein expresses at a higher molecular weight of ~130kDa. I am most certain that this is my protein of interest, as I have blotted with an antibody against the flag tag, as well as an antibody against the protein of interest. I have tried expressing the protein in different cell lines, and in all 3 cell lines that I have tried, it expresses at ~130kDa. Would anyone know why the protein is expressing at almost twice its size. Or are there ways I can troubleshoot this. Please help!!!