Heavy inhibitory solution (HI)

6 mL dissociation medium

60 mg bovine serum albumin (BSA; Sigma)

60 mg trypsin inhibitor (Sigma T6522)

• 1. Warm dissociation medium to 37°C, add BSA and trypsin inhibitor, and mix.

• 2. Incubate at 37°C for ~1 h to completely dissolve.

• 3. Adjust to pH ~7.4 with 0.1 N NaOH (this usually requires ~3 drops of 0.1 N NaOH). Monitor the pH by the color of the solution: Pink is too basic and yellow is too acidic.

• 4. Filter through a 0.2-μm syringe filter.

• 5. Warm the solution in a water bath at 37°C before use. Prepare immediately before use.