Phospholipids (PL) retard and cholesterol (chol) promotes the formation of tumours induced by carcinogenic hydrocarbons.

Not less than 20 — 25 years ago, D ick en s and W e il M a lh e r b e 1> 2 discovered that PL retard, whereas Choi promotes the formation of tumours induced by 3.4benzpyrene. For unexplainable reasons this remarkable finding of utmost importance was never commented in the literature (see, however, A ltm an 3 _6 ) . It should be emphasized that it concerns here with the fact that two very common groups of lipids, representing most familiar components of whatever animal cell. i. c. cell membrane 7_20, are positively capable to influence the still incognito mechanism of carcinogenesis.