Moreover, anticancer drugs (cis-diamminedichloroplatinum/cisplatin [CDDP] or 5-fluorouracil [5-FU]) and FIR knockdown by small interfering RNA (siRNA) increased Cyclin E, whereas siRNA-mediated knockdown of FIRΔexon2 decreased Cyclin E expression in ESCC cell lines (TE1, TE2, and T.Tn). Here, CCNE1 is linked to esophageal squamous cell carcinoma.