PLAT and neoplasm: Similar results were observed in the current studies when C57BL/6.Psl1Adba mice were initiated with 100 nmol DMBA and promoted twice weekly with either 6.8 or 13.6 nmol of TPA (Table 1 and Table 2), further supporting the previous conclusion that the genes underlying the Psl1 locus have an effect on tumor promotion rather than tumor initiation.