MOB3B (MOB kinase activator 3B) is a signal transduction protein that functions as a tumor suppressor across multiple cancer types. MOB3B modulates LATS1 expression within the Hippo signaling pathway, which regulates organ size control and cell proliferation 1. In prostate cancer, MOB3B expression is significantly reduced compared to benign tissue, with low levels associated with aggressive clinicopathological features including elevated PSA, high Gleason scores, and metastatic disease 1. Similarly, MOB3B downregulation in colorectal cancer promotes invasiveness through activation of mTOR/autophagy signaling, while MOB3B overexpression attenuates cell viability, migration, and invasion capacities 2. Mechanistically, KDM5A-mediated suppression of miR-495 leads to YTHDF2-dependent m6A-induced degradation of MOB3B mRNA, ultimately enhancing prostate cancer progression 3. MOB3B DNA hypermethylation shows high diagnostic sensitivity (75-94%) and specificity (84-100%) for prostate cancer, with hypermethylation associated with biochemical recurrence 4. Additionally, MOB3B has been identified as a shared genetic locus between frontotemporal dementia and amyotrophic lateral sclerosis 5. These findings establish MOB3B as a critical tumor suppressor with therapeutic potential in cancer treatment.