The common rabbit IgG isotype has a molecular weight of 150 KD, with two heavy chains (about 50 KD each) and two light chains (about 25 KD each) under the non-reducing condition. Under the reducing condition, the molecular weights are 50 and 25 kD for heavy and light chain respectively.
Please see the link below to review the Uniprot data available for MUC1:
https://www.uniprot.org/uniprotkb/P15941/entry
Please see the link below to review Western Blot results from the Human Protein Atlas database:
https://www.proteinatlas.org/ENSG00000185499-MUC1/summary/antibody#WB