In a mammalian cell line, autophagy is induced with respect to control cells, still the level of beclin-1 is very similar in both conditions, where a particular inducer of autophagy was used to treat control cells.
There is more than only one pathway resulting in autophagy when you look into literature. So maybe autophagy is not induced via Beclin but maybe via PI3K/AKT/mTOR pathway or via eIF4alpha - AFT4 - ATG12 pathway.