sentence: Figure 3A shows that endogenous SRSF6 PTC-containing isoform displayed accelerated decay kinetics in rapamycin-treated cells as compared to the non PTC isoform , suggestive of an increased rate of NMD rather than regulation of AS.To test the direct role of NMD machinery in rapamycin effects , we compared the levels of PTC-containing SRSF6 mRNA isoforms in UPF1-depleted HEK cells treated with or without rapamycin .