The stability and efficiency of cap-dependent translation of PYR1 from PIV and P2IV, and of Venus from VIp19 and V2Ip19 were not established. Generally, protein accumulation seems to be proportional to the mRNA level, which is dependent on mRNA length when the same promoter is used. As shown in Figure 3A and B, the longer V2Ip19 mRNAs were expressed at lower levels than the shorter Venus and VIp19 mRNAs, and accumulation of Venus protein was proportional to the mRNA levels. On the other hand, despite the fact that the P2IV mRNAs were longer they were expressed at lower levels than the shorter PYR1 and PIV mRNAs (Figure 2A), resulting in PYR1 accumulation that was comparable (Figure 2B), but not proportional, to mRNA levels. These results indicate that comparable amounts of PYR1 proteins in PYR1, PIV and P2IV were probably due to protein stability, but not due to efficiency of capdependent translation.