This result and above identified Benzphetamine hydrochloride results of cytoskeleton proteins mutually confirmed cytoskeleton-associated proteins changed in the L-CCG-l resting cysts. These results suggested from one side that there were some differentially expressed proteins between the resting cysts and vegetative cells. In supplementary material, we provided peptide mass fingerprinting and MS/MS spectra for each of the identified specific protein spots in the resting cysts. We only took protein arginine n-methyltransferase as a representative, the peptide mass fingerprinting and MS/MS spectra of this protein were shown in this article. These spectra provided us with more detailed information of analysis and identification of specific proteins in the resting cysts. The process of encystment in ciliates involves overall reconstruction at the cellular level. This process might be controlled or regulated by unknown intracellular signaling pathway including proteins differential expression. Ciliates encystment is clearly a RNA and protein synthesisdependent process. So the resting cyst has its specific proteins. A total of 12 specific proteins including 6 well defined proteins were obtained in our study. 6 specific proteins were type II cytoskeletal 1, keratin, Nop16 domain containing protein, protein arginine n-methyltransferase, epsilon-trimethyllysine hydroxylase and calpain-like proteins. Among these specific proteins, keratin is a cysteine-rich or glycine-rich structural protein and has significant mechanical properties because of its hard fibrous structure. Keratin may regulate the activity of kinases, such as PKC and SRC, via binding to integrin beta-1 and the receptor of activated protein kinase C. Keratins are major contributors of some cells mechanical properties. Type II cytoskeletal 1 is also a keratin. We inferred that keratins could strengthen the mechanical properties of cyst wall and be involved in stability of the cyst wall. Therefore, the keratins improve the ability of survival of the cyst. It is worth mentioning that keratin was found in our identified experiment of cyst wall proteins, which showed that keratin comprised the cytoskeletal component of the cyst wall. In addition, Gutierrez JC et al pointed out that proteins with high content of glycine had been found in cyst wall of some ciliates such as C. sleinii and Paraurostyla sp. Among those which were glycine-rich, keratin should be mentioned.