Fig. 3. Network 1 is a cytokine–chemokine signaling network identified by analysis of the relations among the young ischemic preconditioning up-modulated genes using Ingenuity Pathway Analysis (IPA) software (Ingenuity Systems, Mountain View, CA). In this network, the genes form nodes with connections (gene relationships). The intensity of the node  shading indicates the degree of up-regulation; genes in  unshaded nodes were not identified as differentially expressed in our experiment, but were integrated into the nascent computationally generated network on the basis of the evidence stored in the IPA knowledge base indicating a relevance to this network.  Solid line = direct interaction;  dotted line = indirect interaction. A  solid arrow indicates positive or stimulatory interaction, whereas a  line terminating with a perpendicular indicates an inhibitory interaction. The cell compartments are indicated. These network contained 17 of 31 differentially expressed young ischemic preconditioning gene sets (  table 3 ) and obtained a  p  score of 43. Alkaline phosphatase, laminin, fibrinogen, and collagen (none focus genes) and their network interactions were removed for clarity.