IRAK1 and substance dependence: Using correlation analysis, we found that a considerable portion of the pain pathway-related DEGs, previously known to play active roles in opioid analgesia, tolerance, hyperalgesia, and allodynia, were associated with the harmful effects (such as dependence) linked to morphine and heroin as well as many other drugs of abuse, e.g., Irak1 (encoding interleukin-1 receptor-associated kinase 1) in the enriched Toll-like receptor signaling pathway (Table 1) induced by morphine was correlated with physical dependence at a nominal level of significance (p < 0.05).