In this regard, A3R is often overexpressed and upregulated in tumour cells [97], but not in normal tissues, its inhibitory effect on tumour growth is likely due to a combination of factors, such as inhibition of PI3K/Akt, activation of JNK and p38 MAPK, inhibition of NF-κB, mitochondrial-mediated apoptosis, ROS generation, and cell cycle arrest [97,98,99,100,101,102]. Here, MAPK8 is linked to neoplasm.