Dear Ibrahim,

If you want to lyse the cell later, it should be fine for 24 hours. But if you want to keep the cell viable, then it is not suitable to store it under -20

Dear Ibrahim,

if you want to keep your protein safe without degradation then keep your cells at 20 for about a month (we have already tried, loss of protein in our case is in significant). if you want to keep cells viable then you have to store them under -80.  

If you have kept cell pellet without  any cryo-protectant, then cell will not be viable any more.

If you want to use cell pellet (without any cryo-protectant,) further, it will be nice to keep them at -80 for long term usage. If you want to use them within 15 day then -20 will be OK.

Its for lysis and extraction of DNA, RNA and Proteins not for Viable cells. 

I used it after about 3 weeks and I got good results.

Thank you all ! 

Following

Good answer Dear Dachuri Vinay Kumar

Best Contribution Dear Suresh Chandra Phulara

store it at -80, better and longer