RNA and protein are the two main classes of molecules in the cell. Their interactions widely exists in the cell and especially, are key to post-transcriptional regulation of mRNA stability, translation, localization and splicing. RNA binding proteins (RBPs) can recognize and bind to RNA in a sequence-specific and/or structure-specific way. Previous studies have shown that: sequence-specific RBPs either recognize and bind to unstructured single-stranded RNA or require at least some of their RNA binding sites to be unpaired. Such single-strandness is defined as accessibility of that RNA sequence. My last presentation in June briefly introduced the general background of RNA-Protein Interaction and reviewed a number of representative computational methods in this field. This time I will focus on the sub-class mRNA-protein interaction, and show some of our progress on utilizing mRNA secondary structure to assess the accessibility of RBP binding sites.