SLCO1B1*14 is assigned increased function based on strong evidence in heterozygous and homozygous patients. The lipid-lowering response to fluvastatin is associated with the *14 allele, with greater response in the *14/*14 patients (18781850). The clearance of high-dose methotrexate is significantly faster in patients with two *14 alleles (22147369), and response to low-dose methotrexate is reduced in patients with arthritis (31777781). Exposure to atorvastatin is decreased in heterozygous and homozygous subjects (23311897). The plasma levels of highly sensitive OATP1B1 endogenous substrate GCDCA-3G are significantly lower in *14 carriers than in individuals with the SLCO1B1*1/*1 diplotype (32961594). The *14 allele is associated with increased expression of the transporter in the liver (23311897, 24122874). In vitro studies that normalize the drug uptake to the protein concentration find no increased uptake of rifampin, estrone sulfate, or estradiol 17beta-glucuronide (11477075) and one found decreased uptake of estrone sulfate and ceravistatin (23652407). Therefore, consensus among experts was increased function.