General Motors Co. Chief Executive Officer Mary Barra said on Tuesday the No. 1 U.S. automaker currently has no projects underway with ride-sharing company Lyft, in which it has a 9 percent stake.

Rival automaker Ford Motor Co. (F) said last year it will collaborate with Lyft to deploy large numbers of Ford self-driving vehicles on Lyft’s network by 2021.

Speaking to reporters ahead of GM’s annual shareholders meeting in downtown Detroit, Barra said it could take several years for Japan’s SoftBank Group Corp.’s investment in GM’s autonomous vehicle unit Cruise to bear fruit.

Softbank said last month it will invest $2.25 billion in Cruise, one of the largest and highest profile investments to date in self-driving technology.

When asked about the impact of tariffs imposed by the Trump administration on steel and aluminum imports and ongoing efforts to renegotiate the North American Free Trade Agreement, Barra said the issue was “exceptionally complex.”

“We need to let negotiations continue and be completed,” she said.

But Barra added that “continued uncertainty (over trade) will eventually have an impact.”