Required from Customer

  • Either a minimum of 300 µL of test compound at 10 mM in DMSO, or 5 mg of powder
  • Exact molecular mass of test compound and its salt form
  • Solubility of test compound in Hanks’ buffer
  • MSDS or handling and storage information, e.g., light sensitive, store at -20°C, etc


  • Normalized uptake of test compound at each concentration in OATP1B1-transfected and vector control cells
  • Determination of substrate classification: positive when the ratio of the influx rates in OATP1B1-transfected cells vs. vector control cells >2.0


  • Test compound at 0.5 and 5 µM in HBSSg (pH 7.4) with maximum DMSO concentration not greater than 1%

Assay System

  • OATP1B1-transfected HEK293 cells and vector control cells cultured in 24-well plates

Assay Conditions

  • Measure uptake of test article in-transfected and vector control cells
  • Two concentrations of test article and two sampling time points
  • Treatments per transporter as follows (repeated for each concentration and incubation duration):
  • Transfected cells with test article
  • Vector control cells with test article
  • Perform assay in duplicate (N=2 per treatment)
  • Wells are equilibrated with blank buffer containing 1% BSA prior to initiating the assay
  • Buffer is aspirated and replaced with test article dosing solution
  • Incubate cells for 2 and 10 min at 37°C
  • Terminate the incubation and lyse the cells
  • Analyze cell lysate using LC-MS/MS to determine test article concentration
  • Determine protein concentration in cell lysate and normalize probe substrate concentration to protein content

Batch QC

  • The quality of the cell batch is verified before the cells are used (uptake rate of a probe substrate in OATP1B1-transfected vs. vector control cells)


The customer can request:

  • An in-study positive control for an additional fee


  • The results from this assay are sent to the customer in the ExpressPlus report format, which may include graphical representations of data.