['Maharishi Amrit Kalash (MAK) is an herbal formulation composed of two herbal mixtures, MAK-4 and MAK-5. These preparations are part of a natural health care system from India, known as Maharishi Ayur-Veda. MAK-4 and MAK-5 are each composed of different herbs and are said to have maximum benefit when used in combination. This investigation evaluated the cancer inhibiting effects of MAK-4 and MAK-5, in vitro and in vivo.', 'In vitro assays: Aqueous extracts of MAK-4 and MAK-5 were tested for effects on ras induced cell transformation in the Rat 6 cell line assessed by focus formation assay. In vivo assays: Urethane-treated mice were put on a standard pellet diet or a diet supplemented with MAK-4, MAK-5 or both. At 36 weeks, livers were examined for tumors, sera for oxygen radical absorbance capacity (ORAC), and liver homogenates for enzyme activities of glutathione peroxidase (GPX), glutathione-S-transferase (GST), and NAD(P)H: quinone reductase (QR). Liver fragments of MAK-fed mice were analyzed for connexin (cx) protein expression.', 'MAK-5 and a combination of MAK-5 plus MAK-4, inhibited ras-induced cell transformation. In MAK-4, MAK-5 and MAK4+5-treated mice we observed a 35%, 27% and 46% reduction in the development of urethane-induced liver nodules respectively. MAK-4 and MAK4+5-treated mice had a significantly higher ORAC value (P < 0.05) compared to controls (200.2 +/- 33.7 and 191.6 +/- 32.2 vs. 152.2 +/- 15.7 ORAC units, respectively). The urethane-treated MAK-4, MAK-5 and MAK4+5-fed mice had significantly higher activities of liver cytosolic enzymes compared to the urethane-treated controls and to untreated mice: GPX(0.23 +/- 0.08, 0.21 +/- 0.05, 0.25 +/- 0.04, 0.20 +/- 0.05, 0.21 +/- 0.03 U/mg protein, respectively), GST (2.0 +/- 0.4, 2.0 +/- 0.6, 2.1 +/- 0.3, 1.7 +/- 0.2, 1.7 +/- 0.2 U/mg protein, respectively) and QR (0.13 +/- 0.02, 0.12 +/- 0.06, 0.15 +/- 0.03, 0.1 +/- 0.04, 0.11 +/- 0.03 U/mg protein, respectively). Livers of MAK-treated mice showed a time-dependent increased expression of cx32.'] Does mAK-4 and -5 supplemented diet inhibit liver carcinogenesis in mice?