ERBB2 and cancer: Bhatti et al. also found that the IC50 of VP (1.4 μM) in anti-HER2 C6.5 scFv-targeted VP PDT was about four-fold less than that (5.4 μM) in free VP PDT for the HER 2+ SKOV-3 ovarian cancer line, indicating that scFv targeting improved the effect of VP PDT for that cancer line in vitro by about four fold.