The function of ENSG00000089050 (RBBP9, RB binding protein 9, serine hydrolase) is as follows. Serine hydrolase (Probable) (PubMed:32196348). Catalyzes the hydrolytic activation of amino acid ester of the antiviral prodrug valacyclovir to its corresponding active drug, acyclovir (PubMed:32196348). May negatively regulate basal or autocrine TGF-beta signaling by suppressing SMAD2-SMAD3 phosphorylation (PubMed:20080647). May play a role in the transformation process due to its capacity to confer resistance to the growth-inhibitory effects of TGF-beta through interaction with RB1 and the subsequent displacement of E2F1 (PubMed:9697699). {ECO:0000269|PubMed:19329999, ECO:0000269|PubMed:20080647, ECO:0000269|PubMed:32196348, ECO:0000269|PubMed:9697699, ECO:0000305|PubMed:19329999, ECO:0000305|PubMed:20080647}.