NONCODE (http://www.bioinfo.org/noncode/) is an integrated knowledge database 
dedicated to non-coding RNAs (excluding tRNAs and rRNAs). Non-coding RNAs 
(ncRNAs) have been implied in diseases and identified to play important roles in 
various biological processes. Since NONCODE version 3.0 was released 2 years 
ago, discovery of novel ncRNAs has been promoted by high-throughput RNA 
sequencing (RNA-Seq). In this update of NONCODE, we expand the ncRNA data set by 
collection of newly identified ncRNAs from literature published in the last 2 
years and integration of the latest version of RefSeq and Ensembl. Particularly, 
the number of long non-coding RNA (lncRNA) has increased sharply from 73 327 to 
210 831. Owing to similar alternative splicing pattern to mRNAs, the concept of 
lncRNA genes was put forward to help systematic understanding of lncRNAs. The 56 
018 and 46 475 lncRNA genes were generated from 95 135 and 67 628 lncRNAs for 
human and mouse, respectively. Additionally, we present expression profile of 
lncRNA genes by graphs based on public RNA-seq data for human and mouse, as well 
as predict functions of these lncRNA genes. The improvements brought to the 
database also include an incorporation of an ID conversion tool from RefSeq or 
Ensembl ID to NONCODE ID and a service of lncRNA identification. NONCODE is also 
accessible through http://www.noncode.org/.