The introduction of the mature type of either miR-143 or -145 into colon cancer cells [6,7,20], B cell lymphoma [9], and gastric cancer cells [8,21] results in a significant growth inhibition that occurs in a dose-dependent manner; and the target genes, ERK5 [22] and KRAS [20] for miR-143 and IRS-1 [23] and c-myc [21] for miR-145, were posttranscriptionally down-regulated. The gene discussed is IRS1; the disease is gastric cancer.