extract numbers from cell array and calculate mean

I have a cell array containing numbers and strings. Can someone help me with a code that can calculate the mean of the numbers in each row?

Mix = {

      'U'             [4.7506e+05]    [5.0141e+05]    [5.4067e+05]    [    542976]    [5.7124e+05]
      [3.9810e+05]    [4.4926e+05]    'U'             [    531440]    [5.3655e+05]    'O' 
      [3.0915e+05]    [3.6336e+05]    [3.7107e+05]    [3.8252e+05]    [3.3988e+05]    [4.3384e+05]
      'U'             'U'             'U'             'O'             'U'             [3.7107e+05]         
      'U'             [3.7107e+05]    'U'             [3.8252e+05]    'U'             'O'     }

Answer 1

[Fangjun Jiang]

index=cellfun(@isnumeric,Mix);
Mix(~index)={0};
mean(cell2mat(Mix),2)

[JB]

Thanks a lot Fangjun, that is perfect

[Jan]

+1. I've overseen that the means are wanted for each row.