Table 1. Presence of EGFR T790M mutation at very low frequency in recurrent tumors from case 2.

	No. of clones
Tumor	T790M mutant	Wild type
Primary	0	75
Recurrent 1	2	48
Recurrent 2	1	55
Recurrent 3	0	55
Recurrent 4	0	59

Sequencing of large numbers of cloned PCR products revealed that a minority of alleles within two of four liver lesions contain the T790M mutation.