tokens: MUC1 has often been linked to the Ras - Raf - MEK - ERK cascade [ 12 , 34 - 36 , 46 ] , and at least two mechanisms by which MUC1 can alter MAPK signaling have been described : MUC1 interaction with and phosphorylation by the EGFR family [ 12 , 13 ] , and MUC1 binding to the Grb2 / Sos complex that activates Ras [ 46 ] .