RPL21 and pachyonychia congenita: A pivotal issue about RPL21 as a therapeutic target for PC is the connection between KRAS and the up-regulation of RPL21. Our previous studies showed that the up-regulation of RPL21 gene in PANC-1 cells was because of the long-term suppression rather than the transient suppression of KRAS gene (12), which indicated that RPL21 gene may interact with KRAS gene indirectly.