The effects of cyclin A2 on cisplatin resistance in vivo. (A) Graphic demonstration of tumour growth from HHUA-vec (dashed line) and HHUA-cycA cells (black line) with or without cisplatin (CDDP) treatment (4 mg/kg, intraperitoneally once a week for 4 weeks). Tumours from HHUA-cycA cell (CycACDDP(−), n= 6) grew 1.2 times faster than those from HHUA-vec cells (VecCDDP(−), n= 6) without CDDP treatment. The difference in tumour growth after CDDP treatment between HHUA-cycA (CycACDDP(+), n= 7) and HHUA-vec (VecCDDP(+), n = 7) cells was larger (1.6) than that without CDDP (*P < 0.05). (B) Subcutaneous inoculation of HHUA-cycA cells into nude mice followed by CDDP injection produced a larger mass (right) than that of HHUA-vec cells (left). (C) Haematoxylin and eosin staining of the mouse tumours from HHUA-vec (left) and HHUA-cycA cells (right). Cisplatin treatment resulted in extensive necrosis in HHUA-vec cell tumours (lower left) compared with HHUA-cycA cell tumours (lower right). Scale bars: 15 μm.