EGFR and Pleural effusion: However, control H1299-EGFR-WT cells failed to promote the development of MPE in 100% of mice tested (5/5) at 14 days after inoculation, whereas H1299-EGFR-L858R cells promoted the development of pleural effusion in 80% (4/5) of mice, with volumes ranging from 100 to 1000 μl.