The importance of SLiMs is highlighted by the growing number of instances with relevance to diseases or viruses. Yet, despite their importance and abundance, our understanding of linear motifs is still limited. This is mainly owing to the fact that they are still quite difficult to predict computationally and to investigate experimentally (3, 41, 42) . By better understanding the biology of linear motifs, we hope to increase our insight into diseases and viruses (and vice versa). The ELM resource tries to aid the researcher in the search for putative SLiM instances by providing a feature-rich toolset for sequence analysis. Consequently, with the aforementioned additions and changes, we hope that the ELM resource continues to be a valuable asset to the community. Epithelial Cells Derived from Swine Bone Marrow Express Stem Cell Markers and Support Influenza Virus Replication In Vitro The bone marrow contains heterogeneous population of cells that are involved in the regeneration and repair of diseased organs, including the lungs. In this study, we isolated and characterized progenitor epithelial cells from the bone marrow of 4- to 5-week old germ-free pigs. Microscopically, the cultured cells showed epithelial-like morphology. Phenotypically, these cells expressed the stem cell markers octamer-binding transcription factor (Oct4) and stage-specific embryonic antigen-1 (SSEA-1), the alveolar stem cell marker Clara cell secretory protein (Ccsp), and the epithelial cell markers pan-cytokeratin (Pan-K), cytokeratin-18 (K-18), and occludin. When cultured in epithelial cell growth medium, the progenitor epithelial cells expressed type I and type II pneumocyte markers. Next, we examined the susceptibility of these cells to influenza virus. Progenitor epithelial cells expressed sialic acid receptors utilized by avian and mammalian influenza viruses and were targets for influenza virus replication. Additionally, differentiated type II but not type I pneumocytes supported the replication of influenza virus. Our data indicate that we have identified a unique population of progenitor epithelial cells in the bone marrow that might have airway reconstitution potential and may be a useful model for cell-based therapies for infectious and non-infectious lung diseases. Bone marrow contains a variety of stem cells that include hematopoietic stem cells, mesenchymal stem cells or stromal cells (MSC), and multipotent adult progenitor cells [1] . Many reports using a variety of animal models have demonstrated that bone marrow cells (BMCs) may have a role in the repair and regeneration of injured lung, infarcted myocardium, and damaged bone, tendon and cartilage [2, 3, 4, 5, 6, 7, 8] . BMCs cultured in vitro can differentiate into type I, II, and basal and airway epithelial cells and express the cystic fibrosis transmembrane conductance regulator (CFTR) protein [9] . BMCs have been shown to improve survival and attenuate lung inflammation in bleomycin-and endotoxin-induced lung injury [8, 10, 11, 12] . Following infusion of BMCs in animal models, these cells have been identified as type I and II alveolar epithelial cells, endothelial cells, fibroblasts, and bronchial epithelial cells [12] . However, precise identity of specific subpopulation of BMCs that engraft in the lung parenchyma and have regenerative potential is still not clear.