Mol Cell. 2012 Jun 29;46(6):893-5. doi:10.1016/j.molcel.2012.05.036

Kim YK, Yeo J, Kim B, Ha M, Kim VN.

Short structured RNAs with low GC content are selectively lost during extraction from a small number of cells.

In extraction methods using Trizol, the long RNAs present in the cell lysate act as carrier for the short RNAs, and when initial cell numbers are low or magnesium ions are chelated, structured small RNAs become selectively harder to capture, which causes a bias that can be confounded with key experimental parameters.