Figure 2.

The protein–protein interactions (PPI) network of some phosphoproteins identified by comparative phosphoproteomics studies between human spermatozoa with different levels of motility. PPI are generated by the STRING database (http://string-db.org/, accessed on 14 April 2022). Bubbles show phosphoproteins involved in sperm motility, and lines represent both functional and physical protein associations. The colors of the lines indicate the type of interaction evidenced from different sources: databases (blue), protein homology (grey), high-throughput experiments (pink), co-expression experiments (black), and prior knowledge from research publications (yellow). The absence of a line indicates that no interaction has been detected. Only those interactions with a high confidence interaction score (score ≥0.7 according to STRING indications) are shown.