Prostanoids, including PGD2, PGE2, PGF2α, PGI2, and TXA2, activate nine GPCRs, namely PTGDR1, PTGDR2, PTGER1, PTGER2, PTGER3, PTGER4, PTGFR, PTGIR, and TBXA2R. PTGDR1 downregulation by DNA hypermethylation is correlated with colorectal cancer development [26, 27]. The gene discussed is TBXA2R; the disease is colorectal cancer.