Some of the IC50 value in drug sensitivity databases is lower than 0. I am confused that how should we explain this data. For instance, IC50 of vinblastine (GDSC2:1004) on CCK81 is -5.550494585nM. (in Drug sensitivity IC50 (Sanger GDSC2))
Does it mean that this compound would enhance the cell proliferation instead of suppress the cell viability?
I would appreciate it if someone could give any reply. Thanks in advance