EGFR and cancer: EGF or HB-EGF have also been conjugated to other toxin fragments, with EGF-PE [95], EGF-ricin [90], EGF-saporin [62], and HBEGF-saporin [96,97] also showing specific toxicity to EGFR-expressing cancers in vitro or in vivo while remaining mostly non-toxic to healthy cells.