Cells were washed once with ice cold DPBS (Gibco), rested on ice for 5 minutes, washed one more time with ice cold DPBS and then lysed in 1 ml TROZOL. RNA isolated as described by the manufacturer. csRNA-seq was performed as described in (S. H. Duttke et al. 2019). Small RNAs of ~20-60 nt were size selected from 0.4-3 µg of total RNA by denaturing gel electrophoresis. A 10% input sample was taken aside and the remainder enriched for 5'-capped RNAs. Monophosphorylated RNAs were selectively degraded by 1 hour incubation with Terminator 5'-Phosphate-Dependent Exonuclease (Lucigen). Subsequently, RNAs were 5'dephosphorylated through 90 minutes incubation in total with thermostable QuickCIP (NEB) in which the samples were briefly heated to 75°C and quickly chilled on ice at the 60 minutes mark. Input (sRNA) and csRNA-seq libraries were prepared as described in (Hetzel et al. 2016) using RppH (NEB) and the NEBNext Small RNA Library Prep kit, amplified for 11-14 cycles.