Who directed the episode titled "Playing the Cancer Car"?
CREATE TABLE "table1_28680377_2" (
  "no_in_series" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_million" text
);
SELECT "directed_by" FROM "table1_28680377_2" WHERE "title"='\"Playing the Cancer Car\"';