abnormal protein level abnormal intercellular signaling peptide or protein level abnormal growth factor level MP:0008835 abnormal concentration of any regulatory protein or peptide that is a signaling molecule involved in the process of paracrine communication MPheno.ontology abnormal paracrine peptide factor level These molecules are generally considered factors that are expressed by one cell and are responded to by receptors on another nearby cell. These are distinguished from hormones in that their actions are local rather than distal. abnormal paracrine protein factor level