The Secretariat-General, under the remit of the President, has a high degree of importance in the Commission. It organises meetings, controls the agenda and is responsible for the minutes. The President makes use of this power in his running of the Commission.1
It is often argued that the weekly meeting of "chefs de cabinet" organised by the DG Secretariat-General, prior to the weekly meeting of the European Commission, is where the real decisions in the European Union are made.
References
^Eppink, Derk-Jan; Ian Connerty (translator) (2007). Life of a European Mandarin: Inside the Commission, 1st edition (in English), Tielt, Belgium: Lannoo, p.217-8. ISBN 978-9020970227.