{HEAD ~ IRS1} and IRS2 are {TAIL ~ part} of the insulin or insulin like growth factor signaling pathway 
are
{ HEAD ~ IRS1 } and IRS2 are { TAIL ~ part } of the insulin or insulin like growth factor signaling pathway
HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH