ALK and neoplasm: In general, ALK activates multiple signaling cascades, such as the PI3K-AKT, CRKL-C3G, MEKK2/3-MEK5-ERK5, JAK-STAT and MAPK pathways, and its role in cancer may vary due to many factors, including not only its fusion partners (more than 30 described so far), but also the tumor type or its genetic background (its effects on NB, for example, are dependent on MYCN status) [166].