Sobo will be tasked with driving the growth of the mobile channel at MEC, taking over responsibilities previously held by emerging platforms director Mark Brennan, who has left to become head of mobile at Carat.
Sobo will report to Justin Taylor, managing director of MEC's digital operations.
The agency is also bolstering its social and digital capabilities with the hires of Emma Ellis and James Graver.
Ellis has been hired as social insight director, joining from MPG where she was digital research director.
She will be responsible for bridging the gap between the social media, analytics and insight teams, in order to further integrate social into the planning process.
Graver will work as a digital strategist on the Danone and Wilkinson Sword accounts, having previously been an ideation strategist at UM London since 2007.
Justin Taylor, digital managing director at MEC, said: "They are top talent and their complementary expertise will be a great addition to our experience in the areas when clients are seeking leadership, namely insight, social, strategy and mobile."
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