I accidentally added RNAprotect to my cells, and now the cells are difficult to pellet. What can I do?
FAQ ID -364

If the cells in RNAprotect cannot be collected by centrifugation, please try one of the following suggestions:

1) Add 600 µl Buffer RLT to a maximum of 200 µl sample volume, and proceed with step 3 of the "RNeasy Mini Protocol for Isolation of Total RNA from Animal Cells" in the 
RNeasy Mini Handbook. Load the lysate onto the column in successive aliquots in step 5 of the protocol.

2) If cells are floating on the surface of the RNAprotect Tissue Reagent, try removing the reagent by pipetting from underneath. Leave behind approximately 100 ul of RNAprotect, and add 350 ul Buffer RLT before proceeding with the protocol "RNeasy Mini Protocol for Isolation of Total RNA from Animal Cells". For every 100 ul of cells in RNAprotect, use 250 ul of 96-100% ethanol instead of the 70% ethanol listed in step 4 of the standard protocol.

3) Dilute the sample 10x by adding cold PBS. Pellet cells by centrifugation. Caution: Cells might lyse.

4) Try to pipette the floating cells off the surface.

Note that the above steps are suggestions, rather than official protocol recommendations. Please try a "pilot" run on a test sample first.

For RNA stabilization of cells, we recommend using the RNAprotect Cell Reagent.