PTPA and neoplasm: Excessive accumulation of Cer can activate PP2A, which is a major serine or threonine phosphatase composed of structural subunit A, regulatory subunit B, and catalytic subunit C. PP2A regulates numerous signal transduction pathways by counteracting most kinase-driven signalling pathways to maintain cellular homeostasis [51] and participates in the regulation of various diseases such as tumours, diabetes, heart disease, and human immunodeficiency virus [52,53].