Methods and compounds for increasing sensitivity of assays botulin

A method for detecting the presence of a botulinum toxin, comprising: providing a test with a cell having (a) a molecule with cleavage site that interacts with a portion of botulinum toxin and (b) a reporter which provides a signal observable after cleavage of the molecule at the cleavage site induced by botulinum toxin, wherein the reporter comprises a fluorescent protein; and incubating the cell in a culture medium containing a compound effective isoquinolinyl to increase assay sensitivity by at least 0.5 log compared to a sensitivity of baseline provided by the assay using incubation in the absence of said compound; treating the cell with an amount of botulinum toxin after detecting the signal and correlating the signal with the presence or absence of botulinum toxin, wherein said compound is effective to inhibit PKC both to induce neurite formation.