MTA1 and breast cancer: However, neither overexpression of MTA1 nor inhibition of MTA1 expression had any detectable effect on cell cycle progression or proliferation of HaCaT keratinocytes (Mahoney et al, 2002), MCF-7 (Mazumdar et al, 2001), or MDA-MB-435 breast cancer cells (Nawa et al, 2000).